I quit once and was pretty successful at first, then I heard of these all natural herbal cigarettes at the health food store, started smoking those, it was similar to smoking but lacked that kick I was really craving and my cravings only got strong until I cracked. So, I would say it could do a lot of harm. You've got six years under your belt, the worst of it is definitely over, you've undoubtedly gone through a lot to get to where you are, don't put that at risk.