I was a smoker for 11 years, a box a day. One day I was out of cigs and went out to buy some. As I stopped in front of the shop I thought: What the hell, and went back home. Haven't smoked since and thats over 30 years ago.
A hint: Think back and be proud of your achievements, like -Now I haven't smoked for 10 hours, good, I'm doing fine. -Now I haven't smoked for 2 days, why start again now. -I haven't smoked for a week, I don't need to. And so on.