If you want to live a long, healthy life, make sure you’re among the nonsmokers. Smoking contributes to heart disease, osteoporosis, emphysema and other chronic lung problems, and stroke. It makes breathing during exercise much harder and thus can make activity less enticing. It appears to compromise memory, too.
The news does get better. People who quit smoking can repair some, if not all, of the damage done. After a smoker quits, the risk of heart disease begins to drop within a few months, and in five years, it matches that of someone who never smoked.Source