You can only stop smoking if you really want to.
If you go a week without smoking and then have a fag. You have achieved greatly. Instead of thinking that you have failed, you say "right lets see if I can go longer than a week this time".
Just by giving into the odd fag over a length of time is definately not a failure.

How do I know. Well Idid it 32 years ago when I was smoking 50 a day.
Stopped overnight. Do I ever get a craving - NO