Like with drinking, don't tell yourself you quit forever. You just don't smoke that cigarette NOW. And then you don't smoke the next one.
Keep hard sour candies. Mint toothpicks. Think of the clothes you won't burn holes in. The stink you won't stink. The panic when the pack is empty. The desperation of a cig and no lighter.
You get through a night's sleep without them. You visit hospitals without them.