If you are a heavy smoker, favourite is Dunhill, Marlboro Red......
You can start change it to lighter tar, Marlboro Light......
Maybe after a month, change it to Marlboro Mentol......
Maybe again after a month, change it to Marlboro Mentol Light......
Then maybe again after a month, do not buy any cigarette, and start to borrow from friends if you feel like smoking again......
And then maybe after a month, your friends start to reject lending you any cigarette, then you do not have any cigarette to smoke...... then you can quit smoking.
Believe it or not?