I quit in December of 2003. I mainly quit because I have a niece now, and I don’t want to be her “uncle that smokes”. I think the most important part of quitting is planning ahead. Set a date a few weeks ahead, and then tell everyone you know (especially your family) that you are quitting on that date. Another big thing was to make sure you throw away, break, or dump out all of your smoking paraphenalia (ash trays, lighters, butane, lighter fluid, even take the cigarette lighter out of your car).
I think all the planning is what has kept me a non-smoker since 2003. Good Luck!

