We human beings are heroic in deciding to overcome temptation in the FUTURE, but we're pretty bad at implementing those decisions in the PRESENT. The way to overcome this problem, is to set up contracts with ourselves NOW--while the temptation still lies in the future. This can be done either through 'reward substitution' or by setting up some type of small punishment or fine that we'll have to pay.

(This is the underlying principle behind the TaPHSiC method on GYE)