Skin contains endorphin receptors, which have a pain and anxiety-relieving effect. It's why you rub your skin when you hurt yourself. You're getting blood flowing to the area to help healing - while stimulating other nerve endings to distract you from the pain.
It's also why it feels good to be touched in the right way. So treat yourself to regular massages to help you relax and relieve tension. It will give your skin that feel-good glow and help prevent lines - continuous frowning creates furrows in the skin that form the basis of wrinkles.