I only smoked cigars and cigarillos. My roommate (I was in a dorm in college when I turned 18) didn't mind me smoking, but even as a smoker I abhorred the smell of tobacco smoke so much that I never smoked in my dorm room, only when walking around outside. At least with the cigars, the couple of times I actually inhaled, it made me sick.
After about six months I just had a thought - "Why am I doing this?" - I couldn't answer the question, and that's when I quit.