Different folks have different reactions to noticing new occurrences such as gray hairs or a few fine lines. Of course, there's nothing wrong with looking or feeling a bit older, and it can be fulfilling to celebrate those changes — those smile lines are proof you're living a joy-filled life, after all. But if you want to increase your longevity and keep yourself young at heart for years to come, try these expert-approved strategies on how to stay looking and feeling young.