Kelly McGonigal lists 5 strategies that have been scientifically proven to build willpower. They include:
1) training your willpower physiology
2) forgiving yourself
3) making friends with your future self
4) predicting your failure
5) surfing the urge
Not all of the have to be used, and personally I like 1 and 5 the most. I suggest that you watch and share this video 🙂