I can remember hearing that willpower is a muscle that must be exercised to grow strong.
Now it seems that studies prove that consistently doing one activity that requires self-control seems to increase willpower.
Tighten Your Belt, Strengthen Your Mind
In psychological studies, even something as simple as using your nondominant hand to brush your teeth for two weeks can increase willpower capacity. People who stick to an exercise program for two months report reducing their impulsive spending, junk food intake, alcohol use and smoking. They also study more, watch less television and do more housework. Other forms of willpower training, like money-management classes, work as well.
After giving up candy and chocolate for Lent, I found easier to control my sweet tooth by eating more fruits and vegetables for snacks and that effect has persisted after Easter. Even though I now can eat all the chocolate I want, I 'm still cutting up cucumbers and celery for snacks.