It's not just about your face. Your hair can also show the signs of aging—in the form of dry, brittle, dull, thinning, and, of course, gray strands. The good news? These issues are a heck of a lot easier to fix than wrinkles—and the results happen quickly. We've rounded up the anti-aging shampoos, conditioners, serums, and stylers that will restore your hair to its glossy, full, and youthful status.