If it seems as though you're being bombarded with more and more methods of buying your way into a longer life, full of enhanced and extended vitality . . . well, you are. “I think the amount of science emerging in our understanding of longevity— the reframing of aging as a disease, in a sense, as a phenomenon that can be treated—is really exciting,” says Mark Hyman, M.D., a longevity specialist. His new book, Young Forever: The Secrets to Living Your Longest, Healthiest Life, argues that we can become biologically younger, even as we age chronologically, by eating the right foods, prioritizing sleep and exercise and trying some of the therapies described at right. (He is 63, with an alleged chronological age two decades younger, and plans to still be…