The interventions with the largest effects have been known for decades and are unglamorous. Attention flows almost inversely to effect size, for a simple reason — the big ones cannot be sold.
An afternoon coffee still has an eighth of its caffeine in you the next morning. Anything that loses a constant proportion per period behaves this way — including skills and knowledge.
Lifting weights tears muscle, and the tearing is the point. A small dose of something harmful can trigger a repair response that leaves you stronger — but only under two specific conditions.