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.
We label parcels 'fragile' but have no word for the opposite — not strong, which survives shocks unchanged, but something that improves because of them. Your muscles are the everyday example.
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.