From The Paris Review interview archive: Kurt Vonnegut discusses quitting smoking and then starting again and then quitting and then stating again–
INTERVIEWER: Have you ever stopped smoking?
VONNEGUT: Twice. Once I did it cold turkey, and turned into Santa Claus. I became roly-poly. I was approaching two hundred and fifty pounds. I stopped for almost a year, and then the University of Hawaii brought me to Oahu to speak. I was drinking out of a coconut on the roof of the Ili Kai one night, and all I had to do to complete the ring of my happiness was to smoke a cigarette. Which I did.
INTERVIEWER: The second time?
VONNEGUT: Very recently—last year. I paid Smokenders a hundred and fifty dollars to help me quit, over a period of six weeks. It was exactly as they had promised—easy and instructive. I won my graduation certificate and recognition pin. The only trouble was that I had also gone insane. I was supremely happy and proud, but those around me found me unbearably opinionated and abrupt and boisterous. Also: I had stopped writing. I didn’t even write letters anymore. I had made a bad trade, evidently. So I started smoking again. As the National Association of Manufacturers used to say, “There’s no such thing as a free lunch.”
Biblioklept 
It took me one minute to start smoking, and twenty three years to stop, I started when I was 16 years old. I am now 51 years old.
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I started smoking when I was 9, during 4th grade, it sounds silly but I smoked on average a pack of reds a day. I stopped last christmas because I realized how I already have high blood pressure, and how my grandfather had three heart attacks before letting go.
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I quit smoking march 1, 1981. two things happened. “father of the hydrogen bomb” edward teller came to town and my buddy interviewed him and I went along as the “photographer.” after spending about half an hour with him I thought, “I’m not doing enough with will power. I’m a weinie.” Next day I went to a pal’s house. He said he was going down to an even the American Lung Association was having–a hypnotist. I went and paid twenty bucks. He gave a post-hypnotic suggestion that got me through the first three days. then it got easier. after five days it got easier again. I jogged every day for six months, come rain or shine. I drank no liquor of any kind for over a year. I was free and never went back. live and learn
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