Cameron Diaz, Gwyneth Paltrow, Ben Affleck and more! See the seemingly ageless A-listers celebrating 40th birthdays this year
Josh Duhamel (November 14)
Fergie's hubby makes it a point to squeeze in regular workouts. "You only have one body," the actor (pictured here in 2000) told USA Today in 2011. "I want to stay as young and athletic as I can for as long as I can." He admits his pop star wife helps keep him motivated, too. "When she's been gone for a week, I've been pretty bad about it," he explained of exercising on his lonesome. "I did a 15-minute workout today that was worthless. We definitely push each other."