This next weekend will be 2 months for me.
I started at 24 after breakin my jaw. Couldn't eat or dip snuff, but I could smoke. The jaw healed and the smokes stayed. 1 month before turning 30, I figured it was a good time to quit. I figure that I don't want to be owned by a habit. That and when I look back at life, I don't think I will say, "Jeez, I wish I smoked more..."
Now, my rule is that I don't smoke anything that doesn't get me high.