How long does it take to train for a half marathon?

If you can already run about 3 miles (5 km) without stopping, 12 weeks is enough to train for a half marathon. If you're starting from zero, plan on 4 to 6 months, which is roughly a couch to 5K block followed by a 12 week half marathon block.

A half marathon is 13.1 miles (21.1 km). The work is not especially complicated, but your body needs time to toughen up, and that time can't be rushed.

What 12 weeks looks like

Most plans use three or four runs a week, and the long run does the heavy lifting.

• Weeks 1 to 4: long run goes from about 4 to 6 miles
• Weeks 5 to 8: long run goes from 7 to 10 miles
• Weeks 9 to 10: long run peaks around 11 to 12 miles
• Weeks 11 to 12: taper, where total mileage falls by about a quarter to a half before race day

Your other runs are short and easy, plus maybe one run with some faster pacing. Weekly mileage at the peak is usually somewhere around 20 to 30 miles (32 to 48 km) for first-timers.

Do you need to run the full 13.1 in training?

No. Most plans top out at 10 to 12 miles. The crowd, the taper and adrenaline will get you through the last stretch.

If you have less time

If you have 8 weeks and a base of 10 to 15 miles a week, you can probably do it, but you'll finish it slower and with less margin. If you have 4 weeks, I'd pick a later race. Increases in mileage are the main thing that injures runners, which is why shortcuts backfire.

Bad weeks happen

Miss a few runs from a cold or a busy week, and you don't need to cram. Just pick up where you left off, or repeat the previous week.

To keep the short weekday runs from slipping while the long run grows, League of Fitness matches you daily with someone near your level. Runs synced from Apple Health are scored by heart rate zones, so the easy runs count and not only the long ones.

If you get knee, hip or shin pain that gets worse as you run, rest, and see a doctor or physical therapist before you push on.