Half-Ass It
So here’s a small piece of advice, from one reformed overachiever to another (future) one: half-ass it. Pick a task, something small to start, and do it carelessly. Do half (or less) of what you would ordinarily do. Then see what happens. Consider it an experiment in which your intention is to learn, whatever the outcome. I’m betting your half-assed version is better than most people’s whole ass, but you can test that assertion yourself.
All too often people (including myself) say we’re going to do something, learn something, and then never actually do it. Doing something sloppy to learn something is often more than others do.