“willpower is a muscle. the more you use it, the stronger it gets.” Willpower is a REALLY important thing to have when you are trying to reach a goal, in this case- getting healthy and fit.
Willpower is basically self control, you need to know your limits and know when to stop.
Example: If you eat when you get upset, think before you do. Instead of going for the ice cream or the cookies, go into a different direction and eat some fresh fruit.