Sip from the fountain of youth by making buds a few years your junior. “These friends are typically more active and always up for something,” says Barry Jay, co-founder and director of curriculum of Barry’s Bootcamp. “If you keep up with them, they won’t treat you like you’re older.” Just don’t get carried away when it comes to their partying. Cut back on booze and you’ll see a noticeable difference in your fitness regimen. “If you don’t have to sweat out the alcohol first, you’ll have a better workout,” says Jay.