Because we are 3 times more likely to get lip cancer...reason enough?
As reported on the Men's Health website:
Your lips can have as few as 10 layers of skin, compared with 20 or more elsewhere on your body. "Men are less likely to wear glosses and lipsticks, so their risk of lip cancer is three times higher," says Vilma Cokkinides, director of risk-factor surveillance at the American Cancer Society. Use a lip balm with an SPF of 15 or higher, and reapply it at least every 2 hours if you're in the sun. You should also add a protective swipe in the morning and at night before bed to stop splits and rehydrate the skin."