Somebody, at some point, will tell you that a marathon is 26.2 miles. This is true and completely useless. What they will not tell you is that roughly nineteen of those miles are fine, four are pleasant, and the rest happen to a version of you that you have not met yet.
Most first-marathon advice is written by people who ran 3:15 and found it character-building. This is not that. This is for the ordinary runner — the one whose training plan has already been rearranged twice around work, and who has quietly accepted that the finish photo will show a facial expression best described as unwell. Here is what actually happens.
The training block nobody warns you about
The plan assumes a base you might not have
Marathon plans are typically 16 to 20 weeks, and almost all of them start on the assumption that you can already run for about half an hour without stopping. If you cannot, that is not a failure — it just means your training block has not started yet. Building to 30 continuous minutes first is the least glamorous and most useful thing you will do all year. Skip it and week six of the plan will quietly break you.
Sixteen weeks is a very long time to be slightly tired
Nobody mentions the ambient fatigue. Not injury, not exhaustion — just a low background hum of tiredness that follows you into meetings and into the fridge at 9pm. Your appetite becomes a personality trait. This is normal, and it is why strength work matters: 20 to 30 minutes twice a week is the most underrated injury insurance there is, because it keeps hips and knees honest while your mileage climbs.
The long run becomes a logistics project
By week ten you are not planning a run. You are planning a small expedition: where the water is, which park has a toilet that is actually open, whether the corner shop takes card, what you do if it turns and you are five miles from home in a vest. Long runs stop being about fitness fairly early on. They become rehearsals for problem-solving while mildly depleted, which, conveniently, is the exact skill the marathon tests.
Race week is genuinely strange
Your legs will feel worse before they feel better
The taper is sold to you as a reward. It arrives as a three-week identity crisis. Your legs feel heavy and slightly foreign, partly because stored glycogen binds with water and gives them that dense, sandbagged quality. On top of that, the freshness you are waiting for does not usually turn up until day ten or twelve, because it takes that long to absorb a genuinely hard training block. So you spend the first week of taper convinced you have lost all your fitness. You have not. You are just marinating.
Phantom injuries are a race-week tradition
An ache in a tendon you did not know you owned. A knee that clicks on the stairs. A hamstring that feels “odd”. Taper twinges are almost a rite of passage, and most of them evaporate by Saturday. Real pain that changes how you walk is a different thing entirely and worth a physio’s opinion rather than a forum’s.
Race day: the parts that surprise everyone
The first 10K feels too easy, and that is the trap
You will be fresh, tapered, surrounded by people and carried along by a crowd shouting your name off your race number. Your goal pace will feel like a gentle jog. Every instinct will tell you to bank a few minutes while it is cheap. Those minutes are a loan at a genuinely terrible interest rate, and the repayment window opens somewhere around mile 19. The runners who finish well are almost always the ones who spent the first hour feeling slightly bored.
The wall is mostly an admin problem
Your glycogen stores cover roughly 90 to 120 minutes at marathon effort. Most ordinary runners are out there for four and a half hours — the UK average sits around the 4:30 mark — which is a fairly obvious arithmetic problem. The standard guidance is to start taking carbohydrate in the first 30 to 45 minutes, long before you want any, and keep taking roughly 30 to 60 grams an hour after that. Fuelling when you already feel empty is too late; digestion does not speed up to meet your panic.
Miles 20 to 24 decide the day
This is the stretch nobody trains for, because almost no sensible plan asks you to run it in training. Your longest run is probably 18 to 20 miles, which means the last six are the first six you have ever done. That gap is deliberate — running the full distance in training costs more than it gives — but it does mean the closing stages are genuinely new territory. Expect to renegotiate your goals. Expect to walk through a water station and feel absolutely no shame about it. Walking is a pacing strategy, not a moral event.
Finishing is not the end of the walking
Here is the one nobody mentions. After the finish line there is often another half-mile of shuffling to the baggage lorry, then the meeting point, then the station. On legs that have decided their contract ended at 26.2. Wear something warm in your bag, because you will cool down alarmingly fast, and tell whoever is meeting you to be patient. Stairs will be a problem for two days. Downstairs will be worse than upstairs, which feels like a design flaw.
What to have sorted, kit-wise, by week fourteen
Marathon kit is not about performance. It is about removing every possible source of friction between you and the finish, because four hours turns small irritations into large ones. Socks first: a proper pair of blister running socks is the difference between a hot spot at mile nine and a hot spot at mile nine that you are still thinking about at mile twenty-three. Test them on your longest run, not the day before.
Then the top layer. An Agony running tee that you have already sweated through several times is worth more than anything you buy at the expo, mostly because you already know where it rubs. Same logic for the shorts — whatever chafes at ten miles will chafe considerably more at twenty-two, and this is a solved problem if you read our chafing guide before rather than after. The rest of the range lives in The Kit, but the honest advice is to own less and wash it more.
Common questions
How long should I have been running before starting a marathon plan?
Most plans assume you can already run for around 30 minutes continuously and are managing roughly three runs a week comfortably. If that is not you yet, spend two or three months getting there first. The plan will work much better and hurt considerably less.
Do I need to run 26.2 miles in training?
No. Standard plans peak somewhere between 18 and 20 miles, because the recovery cost of a full-distance training run outweighs the confidence it buys. The taper, the crowd and race-day adrenaline are meant to cover the gap, and for most people they do.
What is a realistic time for a first marathon?
UK averages sit around four and a half hours, and first-timers are frequently slower than that. Finishing is the goal; a time goal on a debut is a good way to turn a hard day into a miserable one. Pick a range rather than a number, and make the top of that range generous.
Why do my legs feel terrible during the taper?
Partly glycogen, which binds water and makes muscles feel heavy and dense, and partly the fact that recovery from a hard block takes longer than most people expect. Heaviness in taper week one is normal. Pain that alters how you walk is not, and is worth a physio’s opinion.
Is it acceptable to walk during a marathon?
Entirely. Plenty of finishers walk the water stations deliberately, and a planned walk at a known point is far more effective than an unplanned collapse at mile twenty-two. Nobody checks the splits afterwards. The medal is not issued conditionally.
Related reading
If you have not got a marathon place yet, start with what to do after the London Marathon ballot rejects you, and have a look at UK races with the most generous cut-off times if the clock is a worry. Not quite ready for the full distance? The best UK half marathons for ordinary runners is the sensible detour, and no less of a day out.
Suffer every mile. Still no medals — although in this one specific case, there is actually a medal. Enjoy it. You have earned the stairs problem.