I quit a pack+ a day habit years and years ago - there are no easy answers, you need a few good friends - use them as a support group so when you're close to caving, you can call one/see one and get past that weak point. Let these people know how important this is to you and have them ask when they see you and offer their support. Don't shoulder this by yourself, get some help/support. You;ll be surprised how much a word or comment at the right time can help you.

Its been long enough for me I no longer get the craving. You can do this, your health is worth the effort. Good luck!!