It's been like 10 or 12 years for me. The one thing I learned the hard way (I had quit, but then started again a few years later) is that I can't even have 1 drag of anything with nicotine in it. That was what started me down the slippery slope the second time. Be vigilant.
I think I'm 31 years tobacco free now. I stopped counting when I accepted that I had pulled it off. I, too, may not smoke even one toke of nicotine. My psychological turning point, having attempted cessation several times, once for as long as a year, was when instead of telling myself I was going to stop smoking, I told myself that I don't smoke anymore. Weird, but it worked for me.
Also perhaps oddly, if I see someone with a tin or Three Castles, I can enjoy a whiff of the aroma without inciting any desire to smoke.
Congratulations to John, and all of us who have managed to get off of this perfetly legal addicitive disaster, and all encouragement in the world to those who would like to abandon tobacco. The upsides appear very quickly, and they are powerfully beneficial and delightful.