It's important to protect yourself from the sun's rays, especially when you're headed out for a long run. Wear technical apparel that comes with a UPF rating (ultraviolet protection fabric), which means it shields skin from UVA and UVB rays. Choose clothing in darker colors, which block more ultraviolet rays than lighter colors. And wear sunscreen year-round. Use a product that provides broad spectrum protection. Be sure to apply the sunscreen 20 minutes before you head out. Use enough sunscreen to fit in a shot glass.