You know, when Ashton Kutcher & Demi Moore got married pretty much everyone had their doubts. With their 15-year age difference and their seemingly very different lifestyles, we never thought they would still be so happily married nearly four years later.

But they are.

"The real trick is putting yourself around people you admire," Ashton tells the new issue of Parade, about staying happy. "That's why I married my wife. I locked in the brightest light in the room."

"My wife and I have an agreement in our marriage, and part of that contract is that we are going to shine our lights on each other," he says. "My relationship with Demi is so solid, thank God, and we're so communicative about the way that we're feeling, that we don't allow space to come between us. I definitely believe that if you stop working at relationships, they go away."

Sounds pretty mature, right? Wondering where the practical joke mastermind behind Punk'd went?

Oh, he's still there.

"I'm still looking for trouble. I'm still disruptive," he smiled. "I'm still doing some things that other people don't like. I hear, 'You're a moron,' about once a day from someone in a genuine way -- not as a joke."