We'd like to think the whole world has given up cigarettes, but the truth is, nearly 20 percent of women in the U.S. still smoke. Besides being the number-one cause of lung cancer, smoking deprives the skin of oxygen and causes skin damage. "Smoking is directly toxic to all of our organs, including our skin and the blood vessels that feed it," says dermatologist Doris Day, MD, author of Forget the Facelift. Not only does it accelerate aging, it increases a person's risk for skin cancer and slows down healing. The good news is, just as you can restore lung capacity by giving up smokes, you can bring your complexion back to health. "I can see the difference within a matter of weeks," says Day.