3. Nail Biting
Do you think nail biting is a harmless habit? Think again. It's not only linked to a higher risk of infections and colds, but, according to Polish researchers, it could also be an obsessive-compulsive disorder. Want to stop? Cut your nails short and regularly chew gum. You could also consider wearing bandages over your fingernails. And, if you're lucky, maybe you'll be able to unlock the mystery as to how bandage-wearing Justin Bieber is able to attract models and actresses. If not, at least you'll be curbing your bad habit, saving your nails, and reducing your risk of infection.