How to Map Out Training for Your First Marathon: A 20-Week Plan That Adapts to You
- May 13
- 24 min read
Updated: Aug 18
Last updated: 2 September 2026
Article contains affiliate links that supports the blog and my cancer charity wook.
Most first-time marathon runners need 20 weeks of structured training, built on a base of running three to four times a week comfortably. Increase weekly mileage by no more than 10%, take a step-back week every third or fourth week, peak with a long run of 20 miles, then taper for two to three weeks. Complete beginners should allow three to six months to build that base first.
Written by Andy Hood, ultra and endurance runner, cancer survivor, and the voice behind runningwestwardho.co.uk.
In this guide
I am running the London Marathon on Sunday 25 April 2027.
I mention that at the top because it changes how I am writing this. I am not looking back at marathon training from a comfortable distance. I am about to start a block myself, alongside roughly 100,000 other people who got a place in the 2027 Double, and I will be making the same decisions you are: when to start, how many days a week, what to do when a week falls apart.
If you are reading this with a place in your inbox, a local marathon in the spring, or just a growing suspicion that you might be capable of 26.2 miles, this is the guide I would want to hand you. It covers the framework, the plan, the fuelling, the mental side, and the honest truth about what actually goes wrong in a training block.
I have been running for years now: ultras, multi-day events, 170 miles along the South West Coast Path to Land's End, two finishes of the 160km Tour du Mont Blanc. Before my cancer diagnosis in 2021 I was a fairly casual marathon runner with a 3:45 finish to my name. Coming back from surgery and chemotherapy, something shifted. My PB is now around 3:20, and almost none of that improvement came from running more miles. It came from finally training properly.
That distinction is what this article is about.
And if you are here looking for a marathon training plan, the one that I train for all my marathons and ultras with then here's the link to Runna and as an official ambassador it will double your free trial to a full 2 weeks of Runna premium - Runna Free Trial
Do You Need to Run a Half Marathon First?
No, you do not need a half marathon finish before you commit to a marathon. You do need a base, and where you are starting from changes how long that base takes to build.
Worth saying that I have never actually entered a half marathon event as part of a marathon build. Not once. What I have done in every single block is run that distance and beyond, several times, as training runs. Look at the plan below and you will see the long run pass 13 miles in week 10 and keep going. The distance gets covered either way. The medal is optional.
That said, there is nothing stopping you from entering a local half on a week where the plan calls for that sort of mileage, and I would encourage it if the idea appeals. It breaks up a long winter block, it gives you a taste of a start line and a field of runners, and it is genuinely good practice for the logistics of race morning.
But you absolutely must listen to the programme. If that week calls for 13 miles at an easy pace, then you go and run 13 easy miles that happen to have a number pinned to your vest. You do not race it. The moment you find yourself chasing the runner ahead or glancing at your watch to see if you can beat last year, you have converted a steady endurance run into a hard effort your plan did not ask for, and you will pay for it in the two weeks that follow. Enter it, enjoy it, run it easy, and take absolutely no pressure into it.
Beyond that, be honest about your starting point. Not to limit yourself, but to plan intelligently.
If you are completely new to running
Your first goal is not the marathon. It is consistency. You need to be running three to four times a week, with some runs reaching 30 to 45 minutes without stopping, before a marathon plan makes any sense at all.
A Couch to 5K programme is a brilliant place to start. Give yourself three to six months here. There is no shame in it, and the runners who get injured or burn out are almost always the ones who skipped this part.
If you are stepping up from a 10K
You have a real foundation. You understand effort, you know what the last kilometre of a race feels like, and you have a routine. The biggest shift is not the mileage, it is the time on your feet, which changes everything from how you fuel to how you recover. Do not assume 10K fitness carries you further without a structured build.
If you are stepping up from a half marathon
This is the most common route and a smart one. You know long runs, you know race nerves. But the jump from 13.1 to 26.2 is still significant, particularly beyond mile 18 where the race genuinely begins. Half marathon training does not prepare your body for the final third of a marathon. That has to be built deliberately.
Wherever you are starting, the answer is the same: build from where you actually are, not from where you would like to be.
The 10% Rule: The One Thing You Must Not Ignore
Whatever your starting point, the most important rule in marathon training is this.
Never increase your weekly mileage or training effort by more than 10% from one week to the next.
It sounds almost too simple to matter. It is not. This rule exists because your body adapts to running stress on its own schedule, and different parts of it adapt at different speeds. Your cardiovascular system improves relatively quickly. Your muscles, tendons, ligaments and bones take considerably longer. That mismatch is precisely where injuries live: your lungs feel ready for more while your connective tissue is still catching up.
So if you are running 30 miles a week, next week caps out around 33. Not 40. Not 35 because you felt good on Tuesday. 33, then reassess.
Build weeks are followed by recovery weeks. Every third or fourth week, mileage should drop by 20% to 30% to let your body absorb the load before building again. These step-back weeks are not optional and they are not a sign of weakness. They are where the adaptation actually happens. Training breaks you down. Recovery is what makes you stronger.
I have learned this the hard way more than once. The miles that feel easiest to add are always the ones that come back to bite you.
When Should You Start Training? Count Back From Race Day
The maths is simple: take your race date, count back the number of weeks you need, and that is the Monday your block begins.
Because I am building towards it myself, here are the dates for the 2027 TCS London Marathon, which runs across two days for the first time in its history: Saturday 24 and Sunday 25 April 2027.
Plan length | Training starts | Who it suits |
16 weeks | Monday 4 January 2027 | Experienced runners with recent half marathon fitness |
18 weeks | Monday 21 December 2026 | Runners with a solid, established base |
20 weeks | Monday 7 December 2026 | Most first-time marathon runners |
24 weeks | Monday 9 November 2026 | Anyone building from a low base |
Base building | September to November 2026 | Anyone not yet running three to four times a week |
Saturday runners, take one day off each date.
If you are training for something else, Manchester, Brighton, Edinburgh, an autumn marathon, a local spring race, the method is identical. Only the dates change.
One thing worth saying about that table. A 20-week block starting in early December means you are established in a routine before January, when everyone else is starting from zero and the gyms are full. That is a genuine advantage, and it is the option I would pick if you have the choice. I've written a further article on a London Marathon training plan.
Your 20-Week First Marathon Training Plan
A 20-week first marathon plan builds through four phases: foundation, development, peak and taper. Weekly mileage rises by no more than 10% at a time, with a step-back week every third or fourth week, peaking at around 41 miles and a 20 mile long run before a three-week taper.
What follows is an example. I want to be clear about that up front, because most sites hand you a table and imply it was written for you.
It was not. It cannot have been. It was written before I knew anything about you: your current fitness, your goal, which days you can run, how you recover, what your legs did last winter. What it gives you is the shape of a marathon build, and the shape is genuinely worth understanding. It is what I would sketch on the back of an envelope if you asked me over coffee.
Use it to learn the pattern. Then read the section after it, because the gap between a good example and a plan built for you is larger than most people realise, and it is the gap I spent years falling into.
Example 20-Week Plan, Four Runs Per Week
This assumes you can already run three to four times a week comfortably, and it is built to get you to a finish line rather than a time.
One thing before you scroll. If you would rather have a programme built around you than an example to work from, try Runna. Two week free trial with code ANDY2, double the standard seven days.
Week | Phase | Long run | Weekly total | Focus |
1 | Foundation | 6 mi | 18 mi | Establish the routine. All easy. |
2 | Foundation | 7 mi | 20 mi | Consistency over pace. |
3 | Foundation | 8 mi | 22 mi | Getting used to four runs a week. |
4 | Step-back | 6 mi | 16 mi | Absorb the load. Not optional. |
5 | Foundation | 9 mi | 24 mi | Long run approaching double figures. |
6 | Development | 10 mi | 26 mi | First double figure long run. |
7 | Development | 11 mi | 28 mi | Begin practising in-run fuelling. |
8 | Step-back | 8 mi | 21 mi | Recovery week. Sleep. |
9 | Development | 12 mi | 30 mi | Add one steady effort session. |
10 | Development | 13 mi | 32 mi | Half marathon distance reached. |
11 | Development | 14 mi | 34 mi | Fuel from 20 minutes onwards. |
12 | Step-back | 10 mi | 25 mi | Physio check if anything niggles. |
13 | Peak | 15 mi | 35 mi | Rehearse race morning breakfast. |
14 | Peak | 17 mi | 37 mi | Full race day kit rehearsal. |
15 | Step-back | 13 mi | 28 mi | Recover before the biggest weeks. |
16 | Peak | 18 mi | 39 mi | Nutrition strategy fully settled. |
17 | Peak | 20 mi | 41 mi | Biggest week. Longest run. |
18 | Taper | 14 mi | 31 mi | Volume drops, intensity stays. |
19 | Taper | 10 mi | 22 mi | Legs will feel strange. Trust it. |
20 | Race week | Race day | ~12 mi + race | Sleep, carbs, patience. |
If you only have 16 weeks, the shape holds and you compress the front end. Start at week 5, which assumes a 9 mile long run is already comfortable, and run through to the finish. Do not compress the taper and do not remove the step-back weeks. Those are the two parts people cut first and the two parts that matter most.
A note on those step-back weeks: they deliberately break the 10% rule, and that is intentional. The rule governs increases between building weeks. After a step-back you return to roughly your previous level plus 8% to 10% rather than starting a fresh climb from the reduced figure.
Easy runs are not junk miles. Around 80% of your weekly mileage should feel genuinely easy, at a conversational pace where you could hold a full sentence without gasping. Only 20% should involve real effort. Running easy runs too fast is the single most common mistake first-time marathon runners make, and it is why so many arrive at week 12 exhausted rather than fit. If you are not sure what easy actually feels like, my guide to Zone 2 running covers it properly, and my running pace calculator will turn your goal time into the actual paces you should be hitting.
Strength Training for Marathon Runners
Two sessions of 20 to 30 minutes a week, on your rest days, will do more for your injury risk than any amount of extra mileage. This is the most commonly skipped part of marathon preparation and one of the most valuable.
Focus on single leg work, glute activation, hip stability and calf strength. Single leg squats, step ups, glute bridges, calf raises, side planks. Four to six exercises, two or three sets each. You do not need a gym, heavy weights, or any equipment beyond a step and a bit of floor.
The reason it matters is mechanical. Running is a series of single leg landings, roughly 30,000 of them across a marathon, and weak hips and glutes mean your knees and ankles absorb load they were not designed to take. Strength work also improves running economy, which means the same pace costs you less.
Reduce lower body volume in the final two weeks before race day, but do not drop it entirely. I've written a comprehensive article on strength training, including exercises for the gym and home.
Getting the Right Running Shoes
Go to a specialist running shop and get properly assessed before your block starts. Not a sports chain, a running shop, where someone will watch you run and talk to you about your gait. The right shoe matters over 26.2 miles in a way it simply does not over 5K, and a shoe that was fine for parkrun can become a problem at 18 miles.
Buy them early, not in week 15. New shoes need 30 to 50 miles of bedding in, and nobody should be breaking in footwear during a taper.
If you can afford two pairs, rotate them. It extends the life of both and varies the stress on your legs slightly from run to run. Replace them somewhere between 400 and 500 miles, which across a 20-week block you may well reach.
What a Training Week Actually Looks Like
That is the shape of the twenty weeks. Here is what a single week inside it actually looks like.
Whether I am training for a marathon or an ultra, the structure of my week is largely the same. What changes is the mileage, and for the longer ultras a much heavier emphasis on endurance and time on feet rather than speed. The scaffolding underneath barely moves.
In a marathon block, my week usually looks like this.
Day | Session |
Monday | Strength session |
Tuesday | Intervals |
Wednesday | Easy run |
Thursday | Speed or tempo session |
Friday | Rest day |
Saturday | Long run |
Sunday | Easy run |
Before you copy it: that is my week, built for an experienced runner after years of getting there. If you are training for your first marathon, the intensity of your programme should look different, and the example plan above sits at four runs a week for good reason. What is worth taking from my week is the structure rather than the volume: hard days spaced apart, one long run, a genuine rest day.
This is also exactly what Runna does well. It meets you where you are and builds you up, rather than handing you somebody else's week and hoping.
Note the Friday. Rest days are part of the training, not a gap in it, and I would put money on that being the line most first-timers find hardest to accept. You do not get stronger while you are running. You get stronger while you recover from running. A rest day is a session, it just happens to be one you spend on the sofa.
Note the Saturday too. My long run sits there rather than on a Sunday, which is fairly unusual, and it works for me because it leaves an easy Sunday to loosen off and a clean start to the week. Yours might need to be a Sunday, or a Wednesday, or split across a Friday evening and a Saturday morning if that is what your household allows. It matters far more that the long run has a settled place in your week than which day you give it.
Why Printed Plans Fall Down
This is your plan, and it has to move around you. If you try to be too rigid about it you will eventually miss a session, feel like you have failed, miss another, and quietly give up somewhere in February. I have watched that happen to a lot of people. The plan bending is not the plan breaking.
And this is exactly where printed plans fall down for me. A PDF has your long run on a Sunday because it has everybody's long run on a Sunday. When your week does not fit that, you are the one who has to redesign it, usually at short notice and usually while tired.
When you set a plan up in Runna you tell it which days you can actually run and which day you want your long run on, and it builds the whole block around that from the start. Then when life gets in the way, and it will, you drag and drop the sessions around on the calendar and the week reshapes itself. No guilt, no arithmetic, no wondering whether you have just broken something.
That single feature is probably why I have stuck with it for over three years.
Where an Example Plan Stops Being Enough
Everything above is honest, and it will get a lot of people round a marathon. But it is worth being straight about what a table on a website structurally cannot do, because these four things are the difference between finishing and finishing well, and between finishing and getting injured in February.
It cannot set your paces. Every session above says easy, steady or hard. Those are efforts, not numbers, and the most common way beginners wreck a training block is running easy days too quickly. A plan that does not know your current fitness cannot tell you that your easy pace is 9:40 rather than 9:00, and no table can work that out for you.
It cannot react. Week 9 lands on a work trip. Your calf tightens on a Tuesday. You sleep badly for a fortnight. The table says 30 miles regardless, because it was printed before any of that happened. Every adjustment is yours to make, and you will be making them while tired, which is exactly when judgement is worst.
It cannot progress from evidence. The numbers were fixed before you ran a single step. If you adapt faster than average you will be undertrained by April. If you adapt more slowly you will be overreaching by week 14. Either way the table carries on as written.
It cannot tell you whether it is working. There is no feedback loop. You find out on race day.
I spent years on plans like this, lifted off websites and printed out. I ran a 3:45 that way. What took me to 3:20 was not more miles, it was training that responded to me: paces set from my actual current fitness, sessions rebuilt when I missed them, and load that adjusted when the data said I was tired rather than when I decided to admit it.
What If You Miss a Week of Training?
Repeat the week you missed rather than jumping ahead to where the plan says you should be. One missed week across a 20-week block costs you almost nothing. Trying to make up the lost mileage is what causes injuries.
This is the question I am asked most, and the answer is more reassuring than people expect. Below is a summary of a more detailed article I wrote about when your marathon training plans gets behind.
One week missed. Pick the plan up by repeating that week, or slot back in at the same level rather than the next step up. Your fitness has not gone anywhere in seven days.
Two weeks missed. Drop back one week and rebuild from there. Do not attempt the long run you would have been on. Cardiovascular fitness holds up reasonably well over a fortnight, but your legs lose their tolerance for time on feet faster than you would like.
Three weeks or more. Reassess honestly. With ten or more weeks left you can rebuild, starting conservatively and accepting a slightly shorter peak long run. With six weeks left and three lost, the kind thing to do is change the goal: finish comfortably rather than chase a time, or move to a later race.
On illness: if it is in your chest, or you have a fever, do not run. Running through a chest infection is how people lose months rather than days. A head cold with no fever is usually fine at easy effort, and if you feel worse ten minutes in, go home.
More broadly, scale the numbers but keep the shape. If 20 miles is already a comfortable week, the plan works as written. If it is not, take every figure down proportionally and hold the pattern.
The deeper point is this. In every training block I have run, marathons, ultras, the Tour du Mont Blanc, I am listening to my body constantly and adapting as I go. I do not push through when something hurts. I do not push through when I am genuinely tired rather than just reluctant. Learning to read those two signals is most of the skill, because ignoring them is how a niggle becomes six weeks off.
I have never once run a block exactly as written. Not for a marathon, not for a hundred miler. Every single one has had weeks knocked out of it. The runners who reach start lines healthy are not the ones whose plans went perfectly. They are the ones who adjusted calmly when they did not.
In practice, that means when something does not feel right, I talk to Runna about adjusting that week. Not abandoning the plan, adjusting it. I flag how I am feeling, move or shorten sessions, and let the plan reshape itself around where I actually am rather than where the schedule assumed I would be. Over a 20-week build that happens more often than you would expect, and it is the biggest single reason I keep arriving at start lines in one piece.
Runna Free Trial: 2 Weeks Free With Code ANDY2
If the last few sections have made the case, here is the practical part.
When you set up a plan in Runna you tell it your goal race, your target time, your current weekly mileage and the days you can realistically train. It builds a complete progressive plan around all of that, sets the pace for every single session from your actual fitness, and delivers the workout to your watch with audio guidance as you run. Then it keeps adjusting, reading each run you sync and reshaping the weeks ahead.
Free PDF plan | Runna (2 weeks free, code ANDY2) | |
Personalised to your goal time | No | Yes |
Paces calculated for every session | No | Yes |
Choose your own training days | No | Yes |
Move sessions when life interferes | No | Yes, drag and drop |
Adapts as your fitness changes | No | Yes |
Race specific, including London 2027 | Rarely | Yes |
Guided audio coaching | No | Yes |
Watch sync (Garmin, Apple, Coros, Suunto) | No | Yes |
Runner specific strength sessions | No | Yes |
Cost | Free | Free for 14 days, then subscription |
I want to be fair to the left hand column. Free plans genuinely work, and plenty of people finish marathons on them. The plan in this article will get you round. What a personalised plan gives you is a schedule that reflects the runner you are becoming rather than the one you were on day one.
As a Runna ambassador I can offer a two-week free trial, double the standard seven days. No payment details are needed to start.
Two weeks is enough to run a long run, a tempo session, an interval session and a strength session, and to see how it handles a missed day. Which, over 20 weeks, you will have. I have been training with Runna for over three years, and my London 2027 plan is being built in it. You can take a deeper dive into the Runna training plans in my article that covers this in more detail.
Why Do Your Legs Feel So Heavy? What Marathon Training Does to Your Body
Marathon training puts stresses on your body that most people have never experienced. Understanding what is happening helps you respond intelligently instead of panicking.
In the early weeks you may feel surprisingly energetic. The volume is not yet high enough to fatigue you deeply. Enjoy it, but do not treat it as permission to do more.
Around weeks four to eight, cumulative fatigue arrives. Legs feel heavy. You need more sleep. This is normal, and it is your body telling you it is working. This is exactly where the 10% rule earns its keep.
As long runs push beyond 14 miles, expect soreness in places you have not felt before: hip flexors, glutes, the outside of the knee. Your musculoskeletal system is adapting to sustained effort, and that process takes time.
I was talking to my sports physio recently and he made an observation that has stuck with me. The most common point at which he sees first-time marathon runners walk through his door is right around the 17 mile mark. That is a telling pattern. By that stage the cumulative stress on tendons, joints and connective tissue has been building for months, and for many runners it is the point where the body finally says enough, if it has not been listened to before then.
If you are approaching that territory and something does not feel right, do not wait and hope. Book in early, before a niggle becomes an injury that costs you the block. I have a monthly sports massage throughout my training to work through tightness and catch anything building. It is one of the best investments you can make.
The other thing worth understanding is glycogen. Your body stores roughly 90 minutes of it at moderate effort. Beyond that you are relying on fat, which is slower to access, plus whatever carbohydrate you take in while running. That single fact is why fuelling during training matters, and why practising your race day nutrition on long runs is not optional.
What to Eat When Training for a Marathon
Get nutrition wrong and the marathon becomes an exercise in survival. Get it right and you cross the line feeling like you ran it rather than endured it.
One thing to say clearly before anything else: a marathon block is not the time to diet.
I understand the temptation. You have taken up a big physical challenge, you are more aware of your body than usual, and a lot of people arrive at marathon training hoping to lose weight along the way. But you cannot ask your body to build a marathon and run a deficit at the same time. Something gives, and what gives is usually your recovery, your immune system and eventually your bones.
If you want the science on this properly, the person I would point you towards is Sian Secc, a registered sports nutritionist who specialises in relative energy deficiency in sport, or REDs, which is essentially what happens when athletes do not take on enough fuel for the training they are doing. She posts about it constantly on Instagram at @siansecc and covers it in detail on her podcast, The Fuelled Runner. Her message is relentlessly consistent and worth internalising: you have to eat.
Underfuelling does not announce itself as underfuelling. It turns up as legs that never recover, sleep that stops working, a resting heart rate creeping upwards, illness after illness, or a stress fracture in week 14 that ends your race. Most runners who experience it think they are simply not tough enough.
Eat enough. Fuel the work. If your weight shifts a bit across twenty weeks as a by-product of the training, fine, but do not make it the goal while you are asking this much of yourself.
Daily nutrition during a training block
As mileage rises so does your energy requirement. Many first-time marathon runners undereat, which produces fatigue, poor recovery and a higher injury risk.
Carbohydrates are your primary fuel: rice, pasta, bread, oats, potatoes. Do not fear them. Aim for a carbohydrate rich meal two to three hours before a long run, and carbohydrate plus protein within 30 to 45 minutes of finishing. Get protein at every main meal for repair and adaptation. Increase your water intake, add electrolytes on longer sessions, and if fatigue persists despite good sleep and food, ask your GP about iron, particularly if you are a female runner.
How to fuel during a long run
Aim for 45 to 60g of carbohydrate per hour for your first marathon, building towards 60 to 90g per hour as your gut adapts across the block. Start fuelling 20 to 30 minutes into any run longer than 90 minutes, before you feel you need it, and repeat at regular intervals. If you wait until you feel empty, you are already behind.
Whatever you plan to use on race day, practise it on every long run. Your gut needs training just as your legs do, and race day is a spectacularly bad time to discover that a particular gel does not agree with you.
My own kit is fairly settled after years of trial and error. I use Precision Fuel and Hydration electrolyte tablets, which handle hydration without interfering with my carbohydrate plan, and their PF 30 and PF 90 gels, which use a 2:1 glucose to fructose ratio and have a mild taste that still works four hours in. On longer efforts I use Infinit :GO FAR drink mix to combine hydration and a chunk of my carbohydrate target in one bottle. My own target sits at the top of that 60 to 90g range, but that adaptation took seasons rather than weeks. Start conservatively.
For the pre-race side of things, carb loading in the 48 hours before you run, I have covered that separately in how to carb up before a marathon or ultra. Worth reading in the taper rather than now.
Hitting the Wall: The Mental Side of the Marathon
Ask anyone who has run a marathon what the real challenge was and they will tell you it was the head.
Miles 18 to 22 are where first timers most often meet the wall. Glycogen is depleted, you have been running for hours, and the mind starts negotiating hard. The voice that asks whether it is really worth it, whether walking would be so bad.
Here is what I know from a lot of miles: that voice lies. It is a protective mechanism, not a reliable signal that you cannot continue. Learning to tell the difference between "this is hard and I should slow down slightly" and "I genuinely need to stop" is one of the real skills of distance running.
Four things that help.
Know your why. Write it down. Running gave me purpose after my cancer diagnosis in 2021, and knowing why I run has carried me through my darkest miles. Yours does not need to be dramatic to be powerful. It needs to be real.
Break it down. At mile 22, do not think about 26. Think about the next lamppost, the next aid station, the next kilometre. Distance running is a long series of small decisions to keep going.
Expect the dark patches. They will come, in training and in the race. Knowing they are coming means you are not shocked when they arrive.
Celebrate the training. Every completed long run is proof your body is adapting. Do not wait for race day to feel proud.
The Taper: Why the Last Three Weeks Feel So Strange
Your mileage drops by 20% to 40% across the final two to three weeks while intensity stays roughly the same. You are not losing fitness. You are shedding accumulated fatigue so that you arrive at the start line fresh rather than merely finished.
Almost every runner I speak to struggles with this phase, and the reason is that it feels like going backwards. The legs get heavy rather than light. Easy runs feel harder than they did in week 14. Doubt arrives, and with it the urge to squeeze in one more long run as reassurance.
Do not. That instinct has ruined more races than undertraining ever has. The fitness is already banked. Nothing you do in the final three weeks will add to it, and plenty of things could subtract.
What the taper does need is attention to the boring parts. Sleep more than usual, because this is when 17 weeks of work actually consolidates. Keep eating properly and increase your carbohydrate intake across the final two or three days rather than attempting one enormous pasta meal the night before. Stay off your feet where you can. Avoid anything new: no new shoes, no new gels, no first-ever sports massage three days out.
Browse Instagram in April and you will see plenty of posts about taper tantrums. They are real, they are universal, and they pass.
Marathon Race Day: How to Pace Your First 26.2 Miles
By the time you reach the start line the work is done. Race day is about executing what you have practised.
Start slower than you want to. The first few miles will feel easy: the crowd, the adrenaline, the taper freshness. Resist the temptation to bank time. The marathon always takes it back, with interest. At a big city race you will also be standing in a start pen for anything up to 90 minutes beforehand, so carry a throwaway layer and eat a small second breakfast while you wait.
Fuel as practised, not according to how you feel in the moment. If you hit the wall, slow down rather than stopping. Take a gel, walk a minute if you need to, talk to yourself firmly and kindly. The miles are in your legs.
And when you cross that line, the exhaustion, the pride, the slight disbelief that you just ran 26.2 miles, that belongs entirely to you. Nobody can train those miles for you. You ran them.
If you are on the London course next April, I will be somewhere out there on the Sunday, probably going through exactly the same negotiations in the final 10K. See you at the finish.
Frequently Asked Questions
How long does it take to train for a first marathon?
Most first-time marathon runners need 20 weeks of structured training, assuming a base of running three to four times a week with some runs of 30 to 45 minutes. Sixteen weeks works for runners with recent half marathon fitness. Complete beginners should allow an additional three to six months to build that base before a marathon plan begins.
How many miles a week should I run?
Most first marathon plans peak somewhere between 35 and 45 miles per week. The figure matters less than the progression: never more than 10% week on week, with a step-back week every third or fourth week. Consistency across months beats any single big week.
Can a complete beginner run a marathon?
Yes, with a realistic timeline. Do not jump straight into a 20-week plan from nothing. Spend several months building a consistent running habit first, then transition into marathon specific training.
What is the 10% rule? Never increase weekly mileage or training effort by more than 10% compared with the previous week. Your cardiovascular system adapts faster than your tendons, muscles and bones, and that mismatch is where injuries happen.
How many days a week should I run?
Four is enough for a first marathon, and it is a schedule most people can sustain alongside work and family. That means one long run, one quality session and two easy runs, with three rest days. Running five or six days a week is fine for experienced runners but adds injury risk for beginners.
What if I miss a week of training?
Repeat the week you missed rather than jumping ahead. One missed week across 20 costs you almost nothing. Trying to make up the lost mileage is what causes injuries.
When should I start fuelling on a long run?
Twenty to 30 minutes into any run over 90 minutes, before you feel you need it. Aim for 45 to 60g of carbohydrate per hour to start, building towards 60 to 90g as your gut adapts. Practise your exact race day strategy on every long run.
How do I know if I am overtraining?
Warning signs include persistently heavy legs that do not recover, elevated resting heart rate, disrupted sleep, declining performance, getting ill more often, loss of motivation, and any pain that worsens during or after runs. If several appear together the answer is genuine rest, not a lighter run.
Should I use a free plan or a training app?
Free plans work and plenty of people finish marathons on them. A personalised app like Runna adds three things a PDF cannot: it builds around your actual fitness and available days, it sets the pace for every session, and it adapts when life interferes. My code ANDY2 gives you two weeks free to judge for yourself.
Is Runna good for London Marathon 2027 training? Yes. Runna builds plans around specific goal races including London, with your target time, current mileage and available training days factored in. The standard trial is seven days; code ANDY2 doubles it to 14. It is what I am using for my own Sunday 25 April place.
About the Author
Andy Hood is an ultra and endurance runner based in North Devon. Following a cancer diagnosis and treatment in 2021, he has completed multiple ultra marathons including a 170 mile run to Land's End on the South West Coast Path and two completions of the 160km Tour du Mont Blanc.
He will run the 2027 TCS London Marathon on Sunday 25 April for The Robin Cancer Trust.
He writes about running and endurance at runningwestwardho.co.uk.
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