You can't smoke all the time when you're a smoker.
Due to work commitments, I'd spend at least 2 hours a day hanging out for my next smoke, even when I was smoking a pack a day.
A month after I quit, I was only hankering for a gasper for half an hour a day, max.
I realised I was spending substantially less time missing nicotine as a non-smoker than when I was smoking full time.
Kind of sealed the deal for me. Now I'll go months without thinking about it.
Alan Carr's 'Easy way to stop smoking' is really good. Helped a lot.