They know cigarettes threaten their health, set a bad example for their children, annoy their acquaintances and cost an inordinate amount of money.
Nobody can force a smoker to quit.
It's something each person has to decide for himself, and will require a personal commitment by the smoker. It is important to identify what you use smoking for and what kind of satisfaction you feel that you are getting from smoking. But the heavy smoker, the person who tries to handle severe personal problems by smoking heavily all day long, is apt to discover that cigarettes do not help him deal with his problems effectively. When it comes to quitting, this kind of smoker may find it easy to stop when everything is going well, but may be tempted to start again in a time of crisis. Physical exertion, eating, drinking, or social activity in moderation may serve as useful substitutes for cigarettes, even in times of tension.