The most common beginner mistake: Running easy days too hard. Most new runners do their easy runs in Zone 3–4 because it "feels more productive." It isn't — it just makes you tired for the sessions that matter. If your plan says easy run, Zone 2 is what it means. Embarrassingly slow is fine.

How to find your real max HR: The formula 220 − age gives a rough estimate (individual variation is large — some people's real max is 10–15 bpm higher or lower). For a more accurate number: after a thorough warm-up, run 3 × 1 km at increasing effort, then sprint the last 400m flat out. The peak number on your watch is close to your true max.

No watch at all? Use the talk test consistently. It works. Elite coaches used it for decades before GPS watches existed. Your body knows what zone it's in.