“If you have a dream, don’t just sit there. Gather courage to believe that you can succeed and leave no stone unturned to make it a reality.” 

I think that what we call "willpower" is a combination of motivation and discipline. Motivation is the desire to do something. Discipline is the skill at making yourself do things you don't want to do for the promise of future reward.

Motivation is a limited resource. Discipline is a muscle you develop. And everybody is limited in their ability to do both, but everybody has the capacity to improve their skill at being disciplined.

REMEMBER "That which we persist in doing becomes easier, not because the nature of the task has changed but because our ability to do so has increased".