For most people, effective "self control" is really placing yourself in situations that don't tempt you, or don't make it easy for you to slip up. [Effective, long-term] Self control happens _before_ the situation, not during.

I love me some chocolate chip cookies, and if there are any in the house I might ignore them when I'm rested, or full, or energized. But at some point I'm going to be tired and hungry and feeling lazy, and those cookies will begin to disappear.

Set up your environment to help you make good decisions.