I have a long and varied history with nicotine.
The day I turned 18 I started buying packs of Camel Reds to feel more grown up. That lasted for 3 years.
I quit for a constellation of reasons.
As I began to realize that I needed to get serious about school/life/career things, I took a look around me at the kinds of people I would need to interact with. None of them smoked cigarettes. During the same period of time, I started to see the value of good health...again, by looking at people who were older, seeing that they were healthy, and did not smoke.
Towards the end of my nicotine addiction, the truth was becoming more clear every day. Succesful people, as a rule, do not smoke cigarettes. Why not? Because to be succesful, you have to be mentally and physically on top of your game. You have to be able to concentrate for long periods without "needing a fix."
As a smoker, I found that I was using cigarettes as something "to look forward to" because, perhaps not surprisingly, I had nothing else TO look forward to. And then once I stopped, I was able to live in the real world again.