The skin on your lips is much more sensitive than the rest of your face. The lips do not contain oil glands like your skin does. This is why the chap so easily.
Lips will crack easily in cold air, sun or wind. When this happens, resist the temptation to pick the peeling skin off your chapped lips.
Mouth breathing can also cause chapped lips. The air that is constantly passing over your lips serves to dry them out.
Toothpaste can be another cause of dry lips due to the ingredient sodium lauryl sulfate. Check your toothpaste label(s). You may also