If you are over 40 and do one thing beyond running this year, make it this. Heavy, not light, twice a week — and a 40-minute session you can do at home.

Seventy-two hours between hard sessions, not forty-eight. The change that matters most after 40, and why the recovery tools that actually work are the unglamorous ones.

Yes — and for most runners over 40 the gains available are large, because they have never actually trained properly. What the decline really looks like, and where the improvement is hiding.

Less than people fear, and differently than people expect. Four changes, and what should stay the same.