Teenagers who pick up a cigarette for the first time may think of it as a harmless experiment. They are young and healthy, and they are unlikely to think that they are on a path to become lifelong smokers. And yet they are wrong. One-third to one-half of teenagers who try even a few cigarettes will become a regular smoker. It's easy to think of smoking as an adult problem. That's who dies from smoking. If someone has not started smoking by age 19 to 21, [he or she] is not likely to ever become a smoker. Nicotine addiction begins when most tob ....