You're already applying sunscreen to your arms, legs, and face at least every two hours ... right? But chances are, you're likely skipping one really important spot: Your lips. Just like the rest of your skin, your lips can get damaged by the sun, leading to sunburn, premature aging, and even skin cancer, which is why you need to know how to protect them. For most people, lip balms with physical sunscreens are a great way to go.