I stopprd smoking cold turkey 27 years ago when I reached 60 cigarettes per day ... The hard part is knowing that I am addicted (I still crave a cigarette when others light up) but for nothing in this WORLD will I go back to being a smoker. Heck, I can smell cigarette smoke in a car when I overtake it on the motorway ... OTOH, I am also the world's worst non-smoker. I have zero tolerance.
I am very happy to be able to say that there are virtually no smokers in my family and friends (when I started, nearly everyone smoked ...).