Photo by Eddson Lens on Pexels
You’ve signed up. The entry confirmation is sitting in your inbox, and somewhere between excitement and mild terror, you’ve started wondering whether you’ve made a terrible mistake. You haven’t. But there are things you’re going to learn about marathon running that no training plan will tell you upfront — and finding them out on race day, at kilometre 34, is a brutal way to do it.
This isn’t a list of generic tips. It’s the stuff that actually catches first-timers off guard: the pacing mistakes that feel fine until they really don’t, the gear decisions that seem trivial until you’re nursing blisters at the finish line, and the mental moments nobody warns you about. Some of it will save your race. Some of it will just mean you suffer slightly less. Both are worth knowing.
One caveat before we start: marathon running is deeply individual. What destroyed someone else’s race might not affect yours at all. But the patterns below show up again and again in first marathons, across all kinds of runners. Take what’s useful and ignore what doesn’t apply.
You will go out too fast. Plan for it anyway.
This is the single most common first marathon mistake, and knowing about it doesn’t make most people immune to it. Race day adrenaline is real. The crowd is loud, your legs feel fresh, and the pace that looked fast on paper feels effortless at kilometre 3. So you let it go. And you pay for it around kilometre 30.
The fix is to set a target pace and treat the first 10km as almost annoyingly easy. If your goal finish time is 4:30, that’s roughly 6:24 per kilometre. Your first 10km should feel like you’re holding back, because you are. That restraint is not wasted energy — it’s stored energy.
A rough rule: if you feel great at halfway, you’re probably on pace. If you feel great at 30km, you may have gone out too slow. If you feel terrible at 30km, you almost certainly went out too fast.
The wall is real, but it’s not inevitable
“Hitting the wall” — that sudden, heavy, everything-hurts collapse in energy that typically strikes between kilometres 30 and 35 — is caused by glycogen depletion. Your muscles run low on stored carbohydrate, your body can’t switch to fat burning fast enough, and you slow down dramatically. Sometimes you stop entirely.
The wall is not some rite of passage you have to accept. It’s largely preventable with two things: pacing (see above) and fuelling. You need to be taking on carbohydrates during the race, not just at the end. Most runners doing a 4–5 hour marathon should aim for 30–60g of carbohydrate per hour from around the 45-minute mark. That means gels, chews, or whatever you’ve trained your gut to tolerate. The key phrase there is trained your gut — race day is not the time to try a new gel brand.
Research published in the Journal of Applied Physiology consistently shows that carbohydrate intake during prolonged exercise improves performance and delays fatigue. Practice your fuelling strategy in training, on your long runs, so your stomach is ready for it on race day.
What you wear matters more than you think
You’ve probably heard “nothing new on race day.” It’s a cliché because it’s true, and people still ignore it. New shoes, a new top, socks from the race expo the night before — any of these can wreck your race through blisters, chafing, or just the psychological distraction of discomfort when you’re already suffering.
Here’s a quick breakdown of the kit decisions that most often go wrong for first-timers:
| Kit item | Common mistake | What to do instead |
|---|---|---|
| Shoes | Wearing race-day shoes with under 50km on them | Use shoes with 80–150km on them — broken in but not worn out |
| Socks | Cotton socks or brand-new technical socks | Wear the same socks you trained in, washed |
| Shorts/tights | New pair bought in the week before | Only wear what you’ve done a long run in |
| Top | Technical tee from the race bag | Test it first — seams and fabrics vary hugely |
| Nipple protection | Skipping it | Body Glide or plasters for anything over 25km, especially in the rain |
| GPS watch | Relying on it entirely for pacing | Use it as a guide, not gospel — GPS drifts on city courses |
Chafing, in particular, is something many runners don’t discover until they’re running for 4+ hours. Thighs, underarms, the back of the neck — anything that rubs for 90 minutes in training will be raw by kilometre 30 of a marathon. Vaseline and Body Glide are your friends.
Your long run isn’t what prepares you — it’s all the long runs
One 32km long run six weeks out doesn’t make you a marathon runner. It’s the accumulation of months of consistent running — the 25km runs, the 28km runs, the back-to-back weekends when your legs were already tired — that builds the physical resilience you need.
Most first-marathon training plans run 16–20 weeks for a reason. If you’ve been training for 10 weeks because life got in the way, that’s still worth something, but you need to go into race day with realistic expectations. Finishing a marathon on 10 weeks of training is possible. Finishing it comfortably is less likely.
Runners World’s training guidance consistently recommends that first-time marathon runners peak their long run at around 32–35km before tapering — not because 35km is the magic number, but because it gives your body (and your mind) enough experience of real fatigue to cope on race day.
The taper will mess with your head
Two to three weeks before your marathon, your training volume drops significantly. This is correct and necessary. It’s also a period when many first-timers experience phantom injuries, low motivation, sudden doubt about whether they’ve done enough, and a strange, restless energy. This is called taper madness, and it’s almost universal.
You will probably feel sluggish and flat in the two weeks before your race. Your legs may feel oddly heavy on your shorter runs. You may convince yourself you’re getting ill. You’re almost certainly not — your body is consolidating the training load you’ve put through it.
The taper is doing the work. Leave it alone.
The mental side goes through phases you won’t expect
Most first-timers think about “getting through the hard part” as a single event — they imagine it’ll be tough somewhere around kilometre 36 and then they’ll be fine. The reality is more fragmented. You might feel brilliant at 20km, rough at 25km, oddly good again at 28km, and then genuinely low at 33km. These windows come and go.
What helps: breaking the race into sections rather than thinking about the full distance. Kilometres 1–10: hold back. Kilometres 11–21: find your rhythm. Kilometres 22–32: stay steady, focus on fuelling. Kilometres 32–42.2: run to the finish, whatever that looks like.
Also worth knowing: you will almost certainly get emotional somewhere near the end. It might be the crowds, it might be the finish line coming into sight, it might be nothing you can identify. That’s fine. It’s not weakness — it’s the result of months of work and hours of effort arriving at once.
Race day logistics will take longer than you plan for
This one is boring but important. First-time marathoners consistently underestimate how long everything takes on race morning: getting to the start, finding the baggage drop, queuing for toilets (queue twice — once when you arrive, once about 15 minutes before your wave starts), getting into your corral.
Build in at least 90 minutes from arriving at the venue to your wave start, especially for large city marathons. Eat your pre-race breakfast 2–3 hours before you run, not 30 minutes before. Aim for something you’ve eaten before a long run — now is not the moment for experimentation.
If you’re doing a big city marathon with a bag drop, pack everything you’ll need post-race in a bag the night before: dry clothes, flip-flops (your feet will thank you), a foil blanket if one isn’t provided, a snack you can face eating when you’re nauseous, and your phone charger.
The Honest Takeaway
- Go out slower than feels right. The first 10km should feel like you’re wasting the good feeling. You’re not. You’re banking it.
- Fuel early and consistently. Don’t wait until you feel like you need a gel — by then, the damage is already starting. Practise your fuelling on long runs before race day.
- Wear kit you’ve already run in. Everything. Socks, shoes, shorts, top. No exceptions.
- Taper madness is normal. The flat, heavy legs and low mood in the final two weeks are not signs you’ve done something wrong. Reduce your mileage, trust the process.
- Finishing is the goal for your first marathon. Not a time, not a negative split, not a comparison to anyone else. Get to the line. Everything else comes with experience.
Next read: Enjoyed this? Read our guide to building your first marathon training plan → /first-marathon-training-plan