The moment the clock started ticking

A runner in a bright teal shirt sprinted past the coffee shop where I was standing one morning. He glanced at his watch and muttered, “One-twenty-five, baby.” That stirred up something familiar, equal parts admiration and hunger. The same spark that had set off my own half-marathon ambition. Could I actually pull that off?

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The goal: 13.1 mi in 1:25:00

Breaking 1:25 at the half means averaging 6:52 per mile (or 4:15 per kilometer). To get there:

• Speed: enough fitness to hold sub-7 paces over distances longer than 5K.
• Endurance: an aerobic base that handles 10 to 12 miles at steady intensity.
• Mindset: trust in your pacing, acceptance of the work, and the grit to push through rough patches.

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Are you ready? Pre-requisites

Check your fitness against what the plan demands:

Requirement	What it looks like
Current half-marathon PB	1:35 to 1:40 or faster. No half on record? You should be able to run 10 mi at 8:00 min/mile comfortably.
Weekly mileage	20 to 30 mi a week, spread over at least 4 days.
Recent consistency	No missed runs for the past 2 weeks; running at least 3 days a week.
Injury-free	No lingering aches that affect your ability to run a moderate distance.

If you’re close but not there, do a 2-week base-building phase first: easy runs, one long run a week, optional cross-training. Then start the main program.

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How the plan works

Five workouts make up the plan, each with its own purpose and effort level:

Workout	Purpose	Typical pace / effort
Easy run	Build aerobic mileage, support recovery	Zone 2, 8:30–9:30 min/mile, conversation pace
Tempo run	Raise lactate threshold (pace you can hold “comfortably hard”)	Zone 3–4, 7:00–7:30 min/mile (about 85–90% max HR)
Interval / speed session	Sharpen leg speed, improve VO₂ max	Short bursts at 5:30–6:00 min/mile (Zone 5), equal rest
Long run	Extend endurance, train fat-fuel use	Zone 2–3, 8:00–8:45 min/mile, finish last 2 mi at goal race pace
Recovery / cross-training	Allow adaptation, reduce impact stress	Light activity (cycling, swimming, yoga) at Zone 1

A GPS watch or app helps with average pace, but train yourself to recognize effort by feel too: conversation-easy for Zone 2, controlled breathing for tempos, labored breathing for intervals.

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12-week training calendar

Week	Mon	Tue	Wed	Thu	Fri	Sat	Sun
1	Rest / cross-train	Easy 4 mi (Z2)	Tempo 4 mi (Z3)	Easy 3 mi (Z2)	Rest	Long 7 mi (Z2)	Recovery 3 mi (Z2)
2	Rest	Easy 4 mi	Interval 5×800 m (5:45 / 800 m)	Easy 3 mi	Rest	Long 8 mi (last 2 mi @ 7:00)	Recovery 3 mi
3	Rest	Easy 5 mi	Tempo 5 mi (7:15)	Easy 3 mi	Rest	Long 9 mi (Z2)	Recovery 3 mi
4	Rest	Easy 5 mi	Interval 6×800 m (5:45)	Easy 3 mi	Rest	Long 10 mi (last 3 mi @ 7:00)	Recovery 4 mi
5	Rest	Easy 5 mi	Tempo 5 mi (7:00)	Easy 4 mi	Rest	Long 11 mi (Z2)	Recovery 4 mi
6	Rest	Easy 5 mi	Interval 4×1 mi (5:50)	Easy 4 mi	Rest	Long 12 mi (last 4 mi @ 6:55)	Recovery 4 mi
7	Rest	Easy 5 mi	Tempo 6 mi (6:55)	Easy 4 mi	Rest	Long 13 mi (Z2)	Recovery 4 mi
8	Rest	Easy 5 mi	Interval 5×1 mi (5:45)	Easy 4 mi	Rest	Long 14 mi (last 5 mi @ 6:55)	Recovery 4 mi
9	Rest	Easy 5 mi	Tempo 6 mi (6:50)	Easy 4 mi	Rest	Long 12 mi (cut-back, Z2)	Recovery 4 mi
10	Rest	Easy 5 mi	Interval 6×800 m (5:40)	Easy 4 mi	Rest	Long 15 mi (last 6 mi @ 6:55)	Recovery 4 mi
11	Rest	Easy 4 mi	Tempo 5 mi (6:45)	Easy 3 mi	Rest	Long 10 mi (race-pace finish)	Recovery 3 mi
12 (race week)	Rest	Easy 3 mi	Tempo 3 mi (goal pace)	Rest	Easy 2 mi	Race day, 13.1 mi @ 6:52/mi	Rest

Swap any easy run for low-impact cross-training (cycling, swimming, elliptical) if you’re drained.

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Detailed workout descriptions

Easy run (Z2)

1. 5 to 10 min of brisk walking or light jogging to wake up.
2. Settle into a conversational pace, somewhere around 8:30–9:30 min/mile.
3. Finish with 5 min of strides (20 to 30 second pickups) to keep your legs sharp.

Tempo run (Z3–4)

1. 10-minute warm-up at easy pace.
2. Hold “comfortably hard” for 20 to 30 min. Short sentences are possible, heart rate around 85 to 90% of max.
3. Wind down with 10 min easy.

Interval / speed session (Z5)

1. 10 to 15 min easy warm-up plus dynamic drills (leg swings, high knees).
2. Run the prescribed distance (e.g. 800 m) at target pace (~5:45/800 m).
3. Recover with an easy jog or walk for the same duration.
4. Complete the reps.
5. 10 min easy cool-down.

Long run (Z2–3)

1. Start easy (Zone 2).
2. After the midpoint, let pace pick up slightly if you feel strong.
3. In the final 2 to 4 miles, hit goal race pace (6:52/mi). That trains your legs to deliver when fatigue sets in.
4. Finish with a 5 to 10 min walk or very light jog.

Recovery / cross-training

Pick a low-impact activity you enjoy: cycling, swimming, elliptical, yoga. Keep intensity low (Zone 1) for 30 to 45 minutes.

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Notes and tips

• Progression: if a week feels overwhelming, repeat it. If it feels easy, add 0.5 to 1 mi to the long run.
• Nutrition: on longer runs, take 30 to 60 g of carbs per hour (a banana and sports drink works). Hydrate, with electrolytes when needed.
• Sleep and recovery: 7 to 9 hours a night. Foam-roll or stretch after harder sessions.
• Pacing: use the talk test for easy runs, heart rate for tempos, splits for intervals. If your paces consistently miss the targets, scale them proportionally.
• Common mistakes: rushing recovery days, ignoring discomfort, or forcing every mile at race pace. Steady work beats all-out effort.
• The plan uses pace zones, step-by-step progression, and scheduled recovery. Adjust as you feel rather than locking in a rigid schedule.

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FAQ

Q: I missed a key workout. What should I do? A: If it was a tempo or interval, swap for an easy run and protect the long run. Don’t stack two hard sessions back to back.

Q: My current half-marathon PB is 1:38. Can I still try this plan? A: Yes. Add a 2-week foundation phase to get weekly mileage up to ~25 mi first.

Q: How do I find the right pace zone without a heart-rate monitor? A: Perceived effort works. Easy means you can chat, tempo means slightly uncomfortable, intervals mean loud breathing and barely able to talk.

Q: I have a minor niggle. Should I keep training? A: Swap the hard day for cross-training or an easy run. If pain worsens, rest and see a professional.

Q: Can I swap a Saturday long run for a Sunday? A: Yes. Just keep at least one rest day before race week.

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The finish line (and beyond)

A 1:25 half teaches you something with every mile: how your body responds to stress, what your mind handles, and the quiet satisfaction of steady progress. Follow the plan, listen to your body, and notice the small wins, a fast interval, a controlled tempo, a long run that felt easier than last week.

Workout suggestion: a goal-pace primer. 1 mi easy, 3 mi at 6:55/mi, 1 mi easy. Gets you comfortable with the target speed in a low-pressure setting.

Get out there, commit to the work, and enjoy the process. A 1:25 half is built one session at a time.

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References

• 1/2 Marathon 12 Week Beginner | running Training Plan | TrainingPeaks (Blog)
• 1/2 Marathon 16 Week Beginner | running Training Plan | TrainingPeaks (Blog)