Nicotine pure and simple, hate smoking but I keep finding myself with a cigarette in hand. And always make weak excuses to myself like "well well I'm going out this weekend it's not a good time to quit." or "I'll just have one now and I can save the box for if someone asks for cigarettes". I tried all sorts of techniques to stop, many which work well but lose interest or get side tracked and forget. I am truly a slave to a wasteful habit.