A rugged appearance might work fine for the Marlboro Cowboy, but most people would rather sport a more youthful look. If you fall in the latter category, make sure cigarettes aren't part of your daily routine. In a study conducted at the University of Michigan, researchers found a direct correlation between smoking and skin damage. Additionally, the longer and more frequently participants smoked, the worse that damage appeared. And while skin damage was particularly apparent in smokers 65 and older, younger smokers experienced it as well [source: BBC].
Smoking harms the skin in a couple of ways. First, it inhibits the production of collagen, a protein that keeps skin smooth and elastic. Second, smoking constricts blood vessels near the surface of the skin. Without collagen and oxygen, the skin develops wrinkles and takes on a leathery appearance. Like many of the negative effects of smoking, the only way to stop the damage is to kick the habit. Ironically, picking up a different, healthier habit is exactly the way to avoid the next mistake on this list.