My father went cold turkey 10 years ago on a first attempt, after smoking fairly heavily for 30 odd years. Took him a few days to get over the physical addition, as he was literal deathly sick. After a month or so, he gained 200 or so lbs which he has yet to shed. My mother still smokes on a light to medium level. He's said that if he were to take up smoking again, he would not even attempt quiting.
Then again he is a guy who took a dozen or so box jellyfish tentacles to the groin and thighs and didn't even peep. >.>