I Quit Accidentally
I smoked for 25 years, 20 a day on average. I knew it was bad for me, but I *liked* it, dammit. Tried to quit a few times, but the longest I stayed off 'em was six months. When the first e-cigs appeared I tried a few brands but never found one that hit the spot in the way a good lungful of carcinogens did.
In 2014 a mate persuaded me to try a new type of e-cig - a big chunky battery with variable-power options, a sizable glass tank with customisable heater/atomiser, and so many flavours of e-liquids it was silly. I gave it a go and after a few days had tuned it to deliver the hit I needed. I smoked my last cigarette in August 2014 and have not had one since.
I decided to cut down on the nicotine content, and by Christmas 2014 was vaping what was basically flavoured water - no drug at all. I was still 'smoking', and enjoying it, but without the risk of Choking Cancerous Death(tm). Job done.
Until summer 2015, when I got a bad cold and didn't vape for a week. I fell out of the habit, and didn't get around to picking it up again. I didn't intend to quit - it was an accident.
Over a year on, and still no urge to vape (or smoke a fag either).