Not the same thing, but...
I smoked for thirty-some years. I had to work at it to get addicted in the first place. I'd quit several times, but always though it was safe to just have one, and went back to consistent smoking. When I finally quit, I spent quite a bit of time thinking about it, and pushing the boundaries. What I learned was that after not smoking all night until about 10AM, when I had that first cigarette, I got a little rush of happiness, like a little bit of euphoria. I suspect any addiction is at least partly due to the serotonin that the drug provokes. When I finally quit, I was quite unhappy/slightly depressed for at least a year. People don't talk about this when it comes to smoking cessation, but maybe they should. It seems like if the "happy" brain chemicals are supplied from outside, the brain forgets how to provide them.