Then there's the psychological addiction. You come to rely on the stimulant effect of nicotine and feel you "need" a cigarette to work, to relax or to calm your nerves.
Hardly a week goes by without a new report on the dangers of tobacco addiction. Don't wait to give up smoking until you're stricken with lung cancer, heart disease, bronchitis or one of the many other smoking-related illnesses.
And you can't rely on switching to a lower tar brand to reduce your chances of getting these diseases. Most smokers on lower-tar brands actually smoke more to compensate for the tar reduction, so end up back where they started.
Mind over matter
TO STOP smoking, you have to conquer both addictions. If you manage to overcome only the physical craving, it's likely you'll reach for a cigarette in a crisis and undo all the hard work.
So you should start by asking yourself why you need a crutch like nicotine. It often helps to observe your habit carefully, even writing down every occasion during the day that you have a cigarette and identifying the reason why you wanted one then.
Thinking about it can help you to cut down, because it breaks the automatic pattern of reaching for the packet. But people who simply cut down almost always go back to their old level.
The only successful way to stop is to choose a time when you feel relatively free from stress, throw away your current packet, grit your teeth and prepare yourself for nicotine withdrawal symptoms.
Substitutes and support
MOST people use food as a substitute when they try to give up smoking and find they put on weight as a result. You also tend to eat more after stopping smoking because your palate, accustomed to being deadened by smoke and tar, becomes cleaner and more sensitive to taste.
If you want to give up smoking without gaining weight, eat fruit rather than sweets and make sure you have regular meals so you're less tempted to nibble.
You can also take up hobbies like knitting or carpentry that satisfy the urge to occupy your hands. And publicise your achievement by colouring in each new day without smoking on a giant wall calendar.
It helps, too, to enlist the support of friends and relatives. Don't let them offer you cigarettes; you can even ask them not to smoke in your home. Avoid places where you'll be tempted, especially pubs and clubs where the drink and the atmosphere will undermine your good resolutions. Head for the non-smoking areas on public transport.
If you find it hard to do it alone, group therapy centres can help by bringing you together with other addicts, to share the problems of addiction and give mutual support for those stopping, as well as expert medical and psychological advice.
There can't be many more rewarding projects than giving up smoking. Feel good about it. Enjoy the cleaner air of "No Smoking" zones in public places. Enjoy being able to get close to people without worrying about the smell of stale tobacco on your breath and body.
Enjoy knowing that you'll live longer, and enjoy the feeling that you're not forcing other people to tolerate your anti-social habit. And pamper yourself with some of the money you're no longer burning.