The Spartans can teach us about discipline by subtraction rather than addition, i.e., what we choose to not focus on.
The gap between knowing what you want and going after it is where fear thrives. You don't need enough courage for the entire journey. You only need courage for the next step.
Your life is designed to get the results you are getting right now.
All successful cultural change (books, movies, public health), has a super-simple two-step loop: