Crux of Overcome the willpower myth by Penelope Trunk:

Willpower is a limited resource. to avoid exhausting it, you can use:

  1. Routine: e.g., automatically brushing your teeth every morning without deciding on it every day.
  2. Canned Response: e.g., when sad call a friend, not try to decide between ice-cream and cookies
  3. Tracking: writing down or telling someone what you did or didn’t do.