[dmd149]

Borrowing from Stoic principles, you must acknowledge that a) there are some things you can control, b) some things you can't, and c) some things you control somewhat.

A professional golfer can't control whether he wins a match, but he can control how well he practices.

Don't get too emotional or attached to outcomes you can't control.

Do focus on "doing your best" at things you can actually control.

This is the point Dan makes, and I think you can make decent progress with this line of thinking and preserve your mental tranquility at the same time.