I smoked for 30 years, and I stopped gradually because cold turkey would not work for me unless murder was legal.
Two tips helped me tremendously.
I understood that the addiction to nicotine is a physical thing. I am not my body (I have a body!) so keeping that in mind, focusing on that fact kept things in perspective for me. I am the boss of my body; my body is not the boss of me even though it seems that way sometimes!
I never told myself "I will NEVER smoke again" - I always, and still do to this day, have the attitude that I could have a smoke whenever I want to.
This eliminates the feeling of deprivation and preserves my power of choice in the matter, both vital aspects to a being in my experience!
From the time I decided to cut down (at one point I smoked 2 packs a day!) until I totally stopped 3 years ago, it took me over 5 years.
I rarely think about having a smoke nowadays, and when I do, it isn't a real nicotine craving that I have to wrestle with. It's more just a "that would be nice right now" thing but I'm not compelled to act on it.