How to Train for Your First Marathon

A marathon is 42.195 kilometres. Most first-timers do not fail it on race day — they fail it in week 14, when an overcooked Tuesday session breaks a Saturday long run that breaks the rest of the block. This guide is built around what actually works: consistency over heroics, slow easy days, honest hard days, and a build long enough to let the body adapt.

How long should the build be?

Sixteen to twenty weeks for a first marathon. Less than 12 and you will start race day under-prepared; more than 22 and the staleness usually outweighs the extra fitness.

Weekly structure

• One long run (16–32 km), almost entirely in Zone 2.
• One quality session — threshold, marathon-pace, or VO₂max depending on the block.
• Two to three easy aerobic runs.
• One full rest day, ideally Monday.

The long run

The long run is the cornerstone. Build it gradually — no more than 10 percent week on week, with a step-back every fourth week. The longest run before race day should be around 30 to 32 km, two to three weeks out. You do not need to run a full marathon in training; you need the durability to survive one.

Fuelling

Above 90 minutes, you need carbohydrate. Practise fuelling in training, not on race day: 60 to 90 grams of carbohydrate per hour, sipped consistently. Test every gel, every drink, every flavour.

Tapering

Drop volume by 30 percent two weeks out and 50 percent the final week. Keep intensity — short race-pace efforts to feel sharp. Sleep more. Eat normally; the carbohydrate load is the last two days, not the last fortnight.

Race day pacing

The single biggest mistake first-timers make is going out too fast. The first 10 km should feel offensively easy. Negative splits (second half faster than first) are the gold standard but rare; even splits are realistic and excellent.