The moment someone stops using tobacco, their body begins to heal itself. Someone can only win by quitting. People who smoke may want to quit, but find it very hard to do. Nicotine is one of the many harmful chemicals found in tobacco that makes it tough to quit smoking. It's called addiction.
Nicotine addiction is very powerful, and is hard to fight off.
It's still possible to win against nicotine in tobacco products, if you team up with others to avoid it. Many kids start to experiment with cigarettes before they become regular smokers. Not all kids who experiment become regular smokers, but many do begin to smoke on a regular basis. The average age that kids have their first cigarette is 12.8 years which means they have thought about it, or tinkered with it at an earlier age. This means it also happens at a younger age, just to a lesser degree.