updated 04/15/2011 AT 11:00 AM ET
•originally published 04/15/2011 AT 3:40 PM ET
“She’s definitely more competitive than [I am],” Duhamel told PEOPLE at Thursday’s New York City Reebok RealFlex footwear launch. “But it’s all in fun.”
He adds: “She’s likely to say, ‘Let’s do one more mile,’ and every time she finishes a workout she says, ‘The glory is mine!’ meaning she actually got up and did it.”
But for the Transformers star, 38, and his Black Eyed Peas singer wife, 36, a friendly dose of competition isn’t necessarily a bad thing. Instead, he says, it helps keep their marriage in tip-top shape.