You probably smoked that first one in part because of peer pressure. Chances are good that you also smoked that first cigarette because of the way it made you feel about yourself. In other words, you smoked it to attain an image. People who smoke have lots of friends.
Smoking is glamorous.
People who smoke do exciting things. People who smoke are good looking. Peer pressure and image probably got you to try cigarettes. But after a while, those reasons tend to lose their importance and no longer greatly influence you. You feel bad when you don't smoke.