No matter your age, no matter your current health condition, as soon as you quit smoking you will immediately begin to experience a number of very important changes. Some are visible from the outside, while others happen unseen by the human eye, but all are significant reasons to quit smoking now. Reason 1: You’ll live longer Taking all other causes into account, smokers are twice as likely than non-smokers to die within 15 years. When you give up cigarettes, you increase your chances of .