A common tactic is the ex-smoker will try to tell himself or herself that he or she does not really want that good cigarette. Well, the problem is at that moment he or she does want it. An internal debate erupts, "I want one, no I don't, one sounds great, not it doesn't, oh just one, not just one!" The problem is that if the ex-smoker focus on one there is no clear winning side. The ex-smoker needs to change the internal discussion.
Don't say that you don't want one when you do, rather acknowledge the desire but ask yourself, do I want the others that go with it. Then do I want the package deal that goes with the others? The expense, social stigma, smell, health effects, possible loss of life. Do you want to go back to smoking, full fledged, until it cripples and kills you? Stated like this it normally is not a back and forth debate. The answer will normally be, "No I don't want to smoke under these terms, and these are the only terms a cigarette comes with.
Normally if viewed like this the debate is over with almost immediately after pulled into focus. Again, if the focus is only on one, you can drive yourself nuts throughout the whole day. If they focus on the whole package deal, you will walk away from the moment relieved to still be smoke free and sufficiently reinforced to never take another puff!