Hmm... An Interesting Idea

I was reading another blog about someone going through dieting, etc.

And she had an interesting "punishment" when she didn't follow her dieting rules.

She (and her roommates) would put a dollar in the jar. Her's was if she went over her daily caloric limit, one roommate's was not enough protein and workouts, and the other's was eating sweets.

BUT, being this as a punishment, they can't spend it on themselves and thought about donating it.

What if I did it as a REWARD system? Each day I stay under calorie limit and workout its a dollar (each) and when its full I can reward myself?

Or would it work better as a punishment? And what would that punishment be??