Smoking is linked to cancer and heart disease. But it is other ingredients in tobacco smoke--not nicotine--that cause these. In fact, nicotine is an extremely effective treatment for several conditions, and can prevent a number of debilitating diseases. It is not lack of willpower but rather a need for nicotine's beneficial effects that prevent so many smokers from being able to quit. Opinions expressed are my own and do not necessarily represent those of any organization I am associated with.