Smoked from 16 to 35ish. Quit cold turkey about 10yrs ago, thats the one and only time I ever tried quitting. I was at about 2 packs a day and closer to 3 packs on days where I would get hammered. I started jogging when I quit, so I really didnt put much weight on from quitting. I went from barely being able to run a block, to running 5k's rather quickly, 3-4 months maybe. Only time it bothered me was when I was drinking or working on a car in my garage. After 6ish months the urges went from a few times a week to once or twice a month. I still love the smell of it though lol. My Dad smoked for 40yrs, quit cold turkey as well.
Every single person I know that did it anyway besides cold turkey went back to some form of smoking or started chewing. Imo, it all boils down to will power, either you have it or you dont, there is no in between. You also really have to want to quit. Cant be telling yourself, I'll quit next Monday, or I'll quit at the end of the month. It doesnt work that way, your lying to yourself. When your ready to quit and dedicate yourself to quitting, you just stop, period, end of story.