I had a long stint in hospital 10 years ago and when I got out I never smoked or drank again (20 a day like you, and basically a piss head). I had cravings for both for a good two years.
Hard to believe it was so normal to smoke everywhere though. Imagine if someone was smoking at the next table in a restaurant now, or even sitting next to you on a plane!
I can vividly remember my junior school teacher chain smoking while keeping an eye on us at break time.