For starters I think that smoking in this day and age given what we know about it is one of the most retarded things that a person can do.
I have no idea how people do it. The same with drinking to such a level where it's daily or almost daily. I have one beer and I feel done for a month. Anything stronger I don't really touch. I've never been the type of person to drink heavily or go to clubs and stuff. So to observe that behaviour around me, it's something I can't comprehend one bit.
I smoked for a while with the whole peer pressure that existed in the 90's but it went out of fashion so to speak in the early 2000's. Even though here in Vietnam and Thailand it is cheap to smoke and basically allowed anywhere, I never feel tempted to get back into that habit. Long-term health risks aside, I remember very well the immediate negative effects such as smokers lung and just feeling out of energy basically all the time.
I didn't find quitting to be all that difficult either. When I see people that are old enough to know better or people who are in their early 20's I am really surprised that people still do this terrible habit.