Strengthen the part of yourself temptation repeatedly tests.

There is usually one specific place where temptation keeps finding you, and it is the same place each time. Willpower in the moment is a poor defence there, because the moment is exactly when you are least equipped. Strengthening that part in advance, when nothing is at stake, is what changes the outcome.

Name the pressure that keeps catching you and decide your response now, in the abstract, before it arrives. A decision made in calm is much easier to follow than one made under pull.