Ep 2: How Hard Should You Run? | 9 Week 10k AND Half Marathon Training Plans | (Follow along) - This Messy Happy

Aug 13, 2025

Intro: This is a quick summary of Ep 2: How Hard Should You Run? from This Messy Happy. It’s a great watch — we’re breaking it down so you can try the workout today. Be sure to check out the full video for all the details.

Key Points:

The week’s theme is intensity: know when to run hard and when to keep it easy.
Two main track sessions showcase different approaches to interval work. Mary does 7 × 400 m repeats at ~5K pace, while Ben does 4 × 1200 m repeats to build speed-endurance. Both are fantastic examples of structured workouts, and you can learn more about the science behind them in our deep dive on Mastering Interval Training: Science-Backed Workouts and How a Smart App Can Personalize Them.
Easy runs should stay in heart‑rate zone 2 (below ~164 bpm) and feel comfortable enough to breathe through the nose for the first 2 km or hold a relaxed conversation.
Recovery runs (Saturday) are 6–7 km at a relaxed effort, focusing on mental refresh rather than speed.
Long run (Sunday) aims for 15 km (for half‑marathoners) or 4–5 km for beginners, keeping a steady ~4:30 min/km pace.

Workout Example:

Track Tuesday (speed session):
- Option A (400 m repeats): 7 × 400 m at just below 5K race pace, with a 60 s easy jog/walk recovery. This type of workout is a cornerstone for runners aiming to get faster. If you’re serious about your next race, explore these proven interval strategies to cut minutes off your 5K time.
- Option B (1200 m repeats): 4 × 1200 m at a comfortably hard pace, 2 min recovery.
Thursday Base Run: 5 km steady in zone 2, focus on nasal breathing for the first 2 km.
Saturday Recovery: 6–7 km easy, conversational effort, no hard surges.
Sunday Long Run: 15 km (or 4–5 km for beginners) at a steady ~4:30 min/km pace. The goal here is to build endurance while keeping your heart rate low and enjoying the scenery. This 15 km distance is a great stepping stone for a half-marathon, and if you’re currently working on shorter distances, our guide to Mastering the 10K provides excellent training plans and pace strategies to help you build up.

Practical Tips:

Use a “nose‑breathing” test for easy runs: if you can’t, you’re too fast.
Aim for a perceived effort of 5–6/10 on easy days; stay below 5/10 on recovery runs.
Adjust paces in the Pacing app to match your own heart‑rate zones and distance goals.

Closing Note: Try the interval or base sessions this week and feel free to customize the paces in the Pacing app to suit your fitness level. Keep the intensity balanced with easy days, and you’ll stay motivated for the long run ahead. Happy running