Picturing a half marathon and thinking, “How hard can 21.1 km be?” Adorable. A half marathon is the distance where you’re fit enough to start… and stubborn enough to finish. It’s also the point where “I’ll just wing it” turns into “why do my calves feel like concrete?”
Preparing well doesn’t mean turning into a monk who lives on oat porridge and motivational quotes. It means showing up consistently, running most of your miles easy (yes, easy—try not to faint), adding a bit of faster work, strength training so your knees don’t resign, and then tapering so you don’t arrive on race day already exhausted.
TL;DR
- Build endurance with progressive long runs and mostly easy Zone 2 running.
- Add 1 quality session per week (intervals/hills/tempo) plus 2 strength sessions.
- Taper 2–3 weeks, practice fueling, and let Garmin Coach boss you around if you like structure.
Half marathon preparation (aka training that doesn’t hate you back)
A half marathon is 13.1 miles (21.1 km). Most solid plans run 6–20 weeks depending on your base fitness, with 3–5 running days per week. The basic recipe across reputable plans is boring—but it works:
- Easy runs in Zone 2 (conversational pace)
- A weekly long run that gradually increases
- A faster workout (intervals, hills, tempo, goal pace)
- Cross-training or rest days
- Strength training 2×/week
Yes, it’s almost offensively unsexy. But unsexy is what gets you to the finish line with your dignity mostly intact.
How long should you train?
Pick your plan length based on what you can do right now, not what you did “in 2019 before life happened.”
- Beginner: 12–20 weeks (especially if your current long run is under 8–10 km)
- Intermediate: 10–14 weeks (you run 3–4×/week already)
- Advanced/goal time: 8–16 weeks (more volume + specific pace work)
Rule of thumb: increase weekly mileage by no more than ~10% to reduce injury risk.
Start with honesty: your base fitness and your schedule
Before you romanticize sunrise runs, do a reality check:
Minimum “ready to start training” checklist
You don’t need to be fast, just consistent.
- You can run/walk for 30 minutes without feeling like you’ve been personally betrayed.
- You can run 3 days a week right now (even if short).
- You can protect at least 1 day/week for a long run.
If you’re brand new, consider a run/walk approach (like Galloway-style pacing). It’s not “cheating.” It’s “not getting injured for ego reasons.”
The weekly structure that actually works
Most successful half marathon plans revolve around 3–5 running days. Here’s a practical framework:
A simple 4-day running week
- Easy run (Zone 2)
- Quality session (intervals/hills/tempo)
- Easy run + strides
- Long run (mostly Zone 2)
Add cross-training (bike, swim, yoga) 1 day/week and strength training 2×/week. Keep at least 1 full rest day.
Zone 2: the pace everyone hates (because it works)
Zone 2 is roughly 60–70% of max HR. It should feel “too easy.” That’s the point.
- You can speak in full sentences.
- Your form stays relaxed.
- You finish feeling like you could do more.
If your easy runs feel like a race, congratulations: you just reinvented burnout.
Easy vs Tempo vs Intervals: what’s the difference?
Because “run faster sometimes” is not a plan.
| Workout type | Effort feel | Main purpose | Example |
|---|---|---|---|
| Easy (Zone 2) | Conversational | Aerobic base, recovery | 30–60 min easy |
| Tempo | Comfortably hard | Lactate threshold, race stamina | 20 min steady tempo |
| Intervals | Hard, controlled | Speed + VO2 stimulus | 6×2 min hard / 2 min easy |
| Hills | Hard uphill, easy down | Strength + running economy | 8×30 sec hill sprints |
A beginner often does: mostly easy + light intervals or hills. Intermediate/advanced: tempo and goal-pace segments become more important.
The long run: your weekly “character development” session
Long runs are where half marathon confidence is built… and where you learn which socks hate you.
How far should the long run go?
Depending on the plan, long runs often peak between 10–16 miles (16–26 km). Many beginner plans build from 5–8 km long runs and progress upward.
Practical targets:
- First-timer: peak around 16–19 km (10–12 miles) can be enough to finish strong
- More experienced: peak 21–26 km (13–16 miles), especially if chasing a time goal
Keep most long runs in Zone 2–low Zone 3. It’s not a weekly audition for pain.
Fueling on long runs (yes, you have to practice)
If your long run goes past ~90 minutes, you’ll likely benefit from carbs during the run.
- Try a gel or chews roughly every 45 minutes after the 90-minute mark
- Hydrate consistently (especially in heat)
- After the run: aim for a carb + protein combo within ~30 minutes
Your stomach also needs training. Surprise gels on race day are how people meet porta-potties spiritually.
Strength training: the boring thing that keeps you running
Two short sessions per week beat one heroic session you’ll “totally do next week.”
Focus on:
- Squats or split squats
- Deadlifts (or hip hinges)
- Calf raises (yes, seriously)
- Core: planks, side planks, dead bugs
Keep it simple. You’re training to run—not to win a powerlifting argument on the internet.
Cross-training and rest: the underrated performance hack
Cross-training (cycling, swimming, Pilates, yoga) builds aerobic fitness while lowering impact. And rest days? They’re where fitness shows up.
If you refuse rest because you’re “disciplined,” you may just be addicted to feeling productive. Cute. Still not a recovery strategy.
Garmin Coach: outsource your decision fatigue
If you like structure and data, Garmin Coach can be a lifesaver. Through the Garmin Connect app, you can select a half marathon plan that adapts based on your feedback, schedule, and progress.
What you’ll typically get:
- Guided workouts (easy, tempo, intervals, long runs)
- Pace suggestions based on recent performance
- Real-time prompts on your Forerunner (or compatible) watch
- Progress tracking using heart rate zones (hello, Zone 2) and workout completion
Is it perfect? No. But it’s consistent, and consistency beats “vibes-based training” every time.
Tapering: the part where you do less and panic more
Two to three weeks before race day, reduce volume by about 20–50% while keeping a touch of intensity. The taper is not laziness; it’s sharpening.
What taper should feel like:
- Fresher legs
- Slightly restless energy
- A strong urge to do something stupid, like “test your fitness” with a 10K time trial
Don’t. You’re not proving anything. You’re saving it.
Race-week and race-day: small details, big payoff
The “don’t be a hero” pacing plan
Start slightly conservative, then aim for a negative split (second half a bit faster).
- First 5 km: calm, controlled
- Middle: settle into goal effort
- Miles/km late in the race: hold form, feed often, stay mentally obnoxious
Yes, miles 8–12 can be full of rage and regret. That’s normal. That’s the sport.
Gear: nothing new on race day
- Shoes: tested on long runs
- Socks: tested (blisters are not a personality trait)
- Nutrition: tested (your gut is not impressed by your spontaneity)
Quick comparison: winging it vs following a plan
Because we both know which one you’ll say you’re doing.
| Approach | Pros | Cons | Best for |
|---|---|---|---|
| Winging it | Feels free | Higher injury risk, inconsistent progress | People who love chaos |
| Structured plan | Progressive overload, better recovery | Requires scheduling | Literally everyone else |
| Garmin Coach plan | Adaptive + guided | Can feel rigid | Data lovers, busy runners |
Internal resources to make training less confusing
If you want extra help (and fewer “what does tempo mean?” moments), these are useful reads:
- Running terms and basics: https://uzjudek.lt/en/blogs/running-glossary-for-beginners-rules-jargon-gear-and-the-stuff-everyone-pretends-to-know
- Preparing for a 10K (great stepping stone): https://uzjudek.lt/en/blogs/how-to-prepare-for-a-10-km-run-tips-for-beginner-runners
- Winter running survival: https://uzjudek.lt/en/blogs/winter-running-without-the-drama-tips-tricks-and-a-tiny-bit-of-common-sense
- Sports events list (find a race): https://uzjudek.lt/en/blogs/sport-events-in-lithuania-a-smarter-sports-list-and-how-to-start-without-losing-your-mind
FAQs
How many days a week should I run for a half marathon?
Most plans use 3–5 running days per week. Beginners often succeed with 3–4 days plus cross-training and strength work.
Do I need to run 21.1 km in training before race day?
Not necessarily. Many first-timer plans peak at 16–19 km. More advanced plans may reach or exceed race distance (up to ~26 km) for specific endurance.
What is Zone 2 running and why is it important?
Zone 2 is an easy, conversational effort (often ~60–70% max HR). It builds aerobic capacity and lets you recover so you can handle long runs and quality sessions.
When should I start using gels or carbs during training?
Practice fueling on runs longer than ~90 minutes. A common approach is a gel/chews about every 45 minutes after that point, plus consistent hydration.
Is Garmin Coach good for half marathon training?
It can be very effective if you want a structured, adaptive plan with guided workouts and pace prompts through Garmin Connect and a compatible watch.
Conclusion
Half marathon prep isn’t magical. It’s a pile of mostly easy running, one weekly long run, a sprinkle of faster work, strength training, and enough rest to let your body actually adapt. Add a smart taper, practice fueling, and either follow a plan or let Garmin Coach handle the “what do I do today?” decisions.
Do that, and you’ll arrive on race day with something rare: fitness and confidence. The suffering will still show up—this is running—but at least it’ll be the kind you chose on purpose.