Winnie Cooper sure has a lot to celebrate! Danica McKellar, who portrayed Cooper on The Wonder Years, turns 40 today. Since her stint on the beloved show, McKellar has gone on to earn a degree in mathematics, pen a handful of nonfiction novels, and got hitched this past year in a Luau-themed wedding. The ageless star is all grown up—and we couldn't be more impressed with her laundry list of accomplishments. But let's be honest: We didn't expect any less from the quintessential girl next door.