What you learn becomes a legacy the moment you teach it to someone else.

Knowledge held privately disappears with you; knowledge passed on keeps operating without you. Teaching is also the point at which you find out whether you actually understand something, because explaining it exposes every gap immediately. You do not need to be an expert, only slightly further along than whoever is asking. Being one chapter ahead is enough.

Teach one thing you know to one person this month. A younger teammate, a sibling, somebody in your class who is stuck. You will hold the thing better afterward, which is the strange part.