The twelve weeks before your first half-marathon

You don't need to run 13.1 miles before race day. Build the long run to 10 or 11, and let the crowd, the taper and the adrenaline carry the last two. Almost every sensible plan works this way, and the ones that have you doing the full distance in training are borrowing risk for no benefit.

That's the single decision that shapes everything else.

Before you start a twelve-week block, you want a base. Roughly: you can run 5k without stopping, and you've been running three times a week for a month or so. If you can't yet, spend six to eight weeks getting there first. Starting a half plan from zero is how people end up with a shin that hurts in week five and a deferred entry in week seven.

What a week actually looks like

Three runs. Four if you like running and your legs are behaving.

• The long run. Saturday or Sunday, whenever you've got two clear hours eventually. Add about a mile a week, and take every third week off the build — go back down by two or three miles to let everything catch up.
• An easy run. 3 to 4 miles, slow. This one is the most commonly skipped and the most useful.
• One harder session. Not a track meet. Something like 6 x 3 minutes at a pace you could hold for maybe 20 minutes, with 90 seconds of walking or jogging in between. Or a 20-minute stretch in the middle of a run where your breathing goes noticeably heavier.

A build might run 4, 5, 6, then back to 4. Then 7, 8, 9, back to 6. Then 10, 11, and into the taper. Two weeks out, your longest run comes down sharply. The week of the race you barely run at all, and you'll feel twitchy and convinced you're losing fitness. You're not.

You're almost certainly running your easy runs too fast

This is the thing first-timers get wrong, and it's worth being blunt about. Easy means you could hold a conversation. Full sentences, not gasped fragments. If you're on your own, try saying the alphabet out loud — if it comes out in chunks, slow down.

It'll feel absurdly slow. You'll be overtaken by someone's dad pushing a buggy. Do it anyway. The reason isn't mystical: easy running is what lets you run four days later without wrecked legs, and the total volume is what builds the endurance, not the intensity of any one session.

Save the effort for the hard session, where it belongs.

Kit, and the parts nobody warns you about

Shoes. Go to a running shop, get fitted, and buy half a size up from your normal size. Feet swell over ten miles and black toenails are a real and very stupid way to spend April. You'll hear 500 to 800 kilometres quoted as a shoe's useful life; the more reliable signal is that your knees or shins start grumbling on runs that never used to bother them.

Sports bra. The band does the work, not the straps. If you can pull the band more than an inch or two off your back, it's too loose, and you'll spend the last three miles of every long run being annoyed by it. Band elastic goes with washing and wear, so a bra you've trained hard in for six or nine months is probably done, even if it looks fine. Two is the minimum, because one is always in the wash.

Anti-chafe balm. Buy it in week one, not week nine. Apply it under the bra band, on the inside of your thighs, at the back of the heel, and anywhere a seam sits. The place it gets you is the one you didn't expect. A hot shower after a long run will tell you, loudly, exactly where you missed.

Socks. Proper running socks, not cotton. This is a five-pound fix for a problem that otherwise ends your race at mile eight.

That's the whole list. You don't need a watch, a vest, or compression anything. A watch is genuinely useful for pacing, but a phone in an armband and a route you've measured will do the same job.

Eating and drinking while moving

Anything under an hour, you don't need fuel. Beyond that, you do, and the general advice sits somewhere around 30 to 60 grams of carbohydrate an hour — one gel or a handful of chews every 30 to 45 minutes, roughly.

Practise this on your long runs. Every single one over 70 minutes. Gels are strange to eat while running, some brands sit badly, and finding out which one disagrees with you at mile nine of the actual race is a miserable way to learn. Test the drink the race is handing out too, if they've published the brand.

The rule for race morning: nothing new. Not the breakfast, not the gel, not the shoes, not the socks.

If you've got a medical condition, you're pregnant, or you're managing something like low iron or a thyroid issue, get the plan looked at by your GP or a sports dietitian before you build the mileage. Training load changes things, and that conversation is a ten-minute appointment, not a research project.

Strength work, twice a week, twenty minutes

Squats, a hinge of some kind, step-ups, calf raises. Single-leg work especially, because running is a single-leg sport and most people are noticeably worse on one side. Add some hip and glute work. You don't need a gym for this.

Skip it and you'll probably still finish. You'll just be more likely to pick up something in the calf or the front of the shin around week eight, when the mileage gets real.

Niggles, and when to stop

An ache that fades once you're warm is usually fine. Pain that gets worse as the run goes on, or that changes how you're running, means stop. Limping through a training run to protect a plan is how a two-week problem becomes a two-month one.

The honest version: if something hurts for more than a few days, see a physio early rather than waiting for it to declare itself. Most running injuries are boringly fixable when they're caught at the grumbling stage.

Race morning

Get there earlier than you think. The toilet queue at a big half is its own event, and it doesn't move.

Pin your number flat across your front with four pins, one per corner, or it'll flap and buzz for two hours. Wear an old jumper you're happy to bin at the start — charity collections take them, and you'll be standing around cold for forty minutes.

Then the part that decides your race. The first three miles will feel too easy if you're doing it right. Everyone around you will surge off the line, and you will feel slow and slightly foolish. Hold your pace. If you go out 30 seconds a mile too fast, you pay it back with interest somewhere around mile ten, and the payment isn't proportional.

Mile ten to eleven is where it gets uncomfortable for nearly everyone. That's not a sign anything's wrong. It's just the bit where it stops being fun and starts being a decision.

And if you need to walk, walk. Plenty of people run a smart half-marathon on a run-walk pattern from the start line — 9 minutes running, 1 minute walking, all the way through — and come home faster and fresher than the ones who tried to run it all and blew up. Pick that method deliberately in week one if you want it, and train with it.

Cross the line, eat something within the hour, and don't get on a train home without walking around for ten minutes first.

Then give it a fortnight before you enter another one. You will want to enter one the same afternoon.