When it doesn't go to plan

Missed one run. Let it go. Don’t make it up, don’t add it to another day.
Missed most of a week. Repeat that week. Don’t jump ahead to stay on schedule.
Missed two weeks or more. Drop back to the start of the current block and rebuild.
A week feels genuinely too hard — not unpleasant, but leaving you flat for days. Repeat it at 80% of the listed distances before moving on.
Forced to choose which run to protect: long run first, medium-long second, quality last. Volume is what makes the marathon; the Tuesday session is what makes it fast, and fast is the thing you can afford to lose.

Stop the session

Sharp or pinching pain anywhere. Pain that grows as you run. Anything that changes how you move. Chest pain or dizziness. Pain above roughly 3 out of 10. Anything still present 48 hours later means you go back a week — not forward with a better attitude.

At 66 km a week the tissues that fail first are the calf, the Achilles, the shin and the plantar fascia, roughly in that order. Bone stress injuries announce themselves as a small point of pain that gets worse during a run rather than warming up. That one is not negotiable — stop and get it imaged.

Carry on

A dull ache that warms up and clears within ten minutes and is gone the next morning. Heavy legs on a Sunday after a Saturday long run. General fatigue in weeks 11 and 13. Being bored on easy runs — that means you’re doing them right.