If you can’t run 3 miles without stopping, your first race should be a 5K. If you already run 3 miles three or four times a week, a 10K or half marathon is fair game.
That’s the whole decision rule. The rest of this post shows why it works and where people go wrong.
Why a Shorter First Goal Protects You
New runners get hurt a lot. A pooled analysis of 13 studies found novices had 17.8 running injuries per 1,000 hours of running. Recreational runners had 7.7 (Videbaek et al., 2015). In short: beginners get hurt about 2.3 times as often for every hour they run.
Think of your body as a house getting a new floor. The bones and tendons are the beams. They adapt slower than your lungs do. Your breathing feels ready in week four. The beams aren’t.
A shorter goal gives those beams more time to catch up. It also gives you a finish line you can actually reach.
Fit beats ambition.
Couch to 5K: What It Delivers
The NHS Couch to 5K plan runs 9 weeks, with 3 sessions a week and rest days between them. Week 1 starts with 1 minute of running and 1 minute 30 seconds of walking. It ends with 30 minutes of continuous running. You can take longer if you need to (NHS).
The plan is gentle. Real life is rougher. In a UK study of 110 people on a modified 9-week plan, only 27.3% finished. About 19% got injured, and injury was the reason for 11 of 15 drop-outs interviewed (Relph et al., 2023). The sample was small, mostly women, and from one site.
The strongest warning sign was a past injury. Runners with a previous injury were far more likely to quit, with an odds ratio of 7.56. Translation: if you’ve been hurt before, you need a slower start than the plan assumes. Think of it this way. A runner with a past injury has a weak spot that the plan doesn’t know about. Repeat easy weeks until the old trouble spot stays quiet, then move on. Waiting an extra two weeks costs you little. Quitting at week five costs you the whole plan.
5K vs 10K vs Half Marathon at a Glance
Here’s how three popular beginner plans compare. Weeks and mileage come from the NHS and Hal Higdon’s novice plans. The weekly time row is our rough estimate.
| 5K (Couch to 5K) | 10K (Higdon Novice) | Half marathon (Higdon Novice 1) | |
|---|---|---|---|
| Plan length | 9 weeks | 8 weeks | 12 weeks |
| Runs per week | 3 | 3, plus 2 cross-training days | 3 to 4, plus cross-training |
| Longest training run | 30 minutes | 5.5 miles | 10 miles |
| Peak weekly running | About 90 minutes (estimate) | About 10.5 miles | About 20 to 23 miles |
| Assumed starting base | None | Some jogging and walking | Run 3 miles, 3 to 4 times a week |
| Weekly time, approx. | 1.5 to 2 hours | 2 to 3 hours | 4 to 5 hours |
Look at the base row. The half marathon plan isn’t a couch plan. Hal Higdon himself says that if you can’t run 3 miles that often, you should pick a shorter race first. A “couch to half in 12 weeks” promise doesn’t come from the plan’s author.
The 10K is the quiet middle step. Higdon’s Novice 10K runs 8 weeks. Its long run grows to 5.5 miles, and peak weekly running is about 10.5 miles. In short: you run roughly half the weekly distance of the half marathon plan. Your tendons get a real workout, but not a brutal one. If you just finished a 5K plan, this is the step that fits. If you’re unsure whether you’re ready for 13.1 miles, the 10K tells you honestly.
Which Goal Fits You
| Where you are today | Weeks to race | Best first goal |
|---|---|---|
| Can’t run 5 minutes | 8 to 12 | 5K |
| Can run 30 minutes | 8 to 12 | 5K or 10K |
| Run 3 miles, 3 to 4 times a week | 12 or more | 10K or half marathon |
| Returning after an injury | Any | 5K, then build up |
Take a runner I’ll call Dana, 41. She wanted a half marathon in 12 weeks. She’d walked a lot but hadn’t run in two years, and she’d had shin trouble before. Her longest run was 12 minutes.
She started with a 5K plan instead. Nine weeks later she ran 30 minutes straight. She then spent 8 weeks on a 10K plan. Six months after day one, she lined up for her half with a base of 3-mile runs, four times a week. She finished it.
Dana’s path took longer. It also kept her running.
What the Research Says About the 10% Rule
You’ve heard it: never raise weekly mileage by more than 10%. The trial evidence is thin. In 532 novices training for a 4-mile event, a graded 13-week plan built on the 10% idea led to 20.8% injured. A standard 8-week plan led to 20.3% (Buist et al., 2008). In short: the slow plan didn’t protect anyone.
Roughly 1 in 5 novices got hurt either way. The plan style mattered less than who was on it.
A newer 2025 analysis of Garmin data points somewhere else. It linked a single run well beyond your recent longest to more overuse injuries. So don’t jump from a 4-mile long run to 8. That’s an observational finding, not a guarantee, so treat it as a sensible guardrail. Small extras can help too. Five minutes of daily hopping builds tolerance in tiny doses.
Why a Near Goal Keeps You Going
Psychology research suggests close goals help people stick with hard tasks. The classic study used children learning maths, not runners. So it’s a mechanism, not proof. The idea is simple: a finish line nine weeks out feels reachable. A finish line six months out feels like a story.
Pick the near one first. Then pick the next.
Common First-Race Mistakes
Most beginners don’t fail from lack of effort. They fail from a few repeat errors.
- Picking the race before checking the base. The distance sounds great. Your legs disagree.
- Running every session hard. Easy runs should feel boring. If you can’t talk, slow down.
- Skipping rest days. The NHS plan puts rest between runs for a reason.
- Treating a missed week as failure. Repeat the week and carry on. The plan allows longer.
- Ignoring old injuries. A past injury was the strongest quit signal in the UK study.
A 12-Week Realism Check
Answer these before you register:
- Can you run 3 miles today? If not, choose a 5K.
- Have you been injured in the last year? If yes, start with the 5K plan and go slower than the schedule.
- Do you have 4 to 5 hours a week? If not, a half marathon plan won’t fit.
- Do you have at least 12 weeks? If not, a shorter race is the safer bet.
Once you’re running, keep most runs easy. Zone 2 training explains why that pace builds your base without wrecking your legs. When race day nears, pace by durability, not by hope.
AthleteOS asks about your current running, your injury history, and how many hours you have. Then it checks your goal against that. If you pick something too big, it tells you why and points you to a shorter race or a later date. You can start a 14-day trial and set your first goal here.
Your first race is a starting line. Choose one you’ll reach.