Though he's dealing with that fact he's just turned 40, proud papa Diddy has an even bigger issue on his plate: keeping up with his twin girls (with ex Kim Porter), D'Lila Star and Jessie James, who turn 3 on Dec. 21.

"They're talking a lot more and they're very demanding," says the Grammy-winning hip-hop star and entrepreneur. As for what they demand from their dad: "Just time," he says. " 'Sit down. Don't go anywhere, stay here, do this.' They give me a lot of orders."

And despite his demanding schedule – in addition to managing his business empire, Diddy is working on a new album, Last Train to Paris, and continuing to promote Ciroc vodka – he says his girls can always persuade him to take a break.

"When they tell me to sit down," he says, "everything else gets put to the back burner."

As for hitting the milestone, "It was a shock for me, because my spirit and my energy are so young,” he says. “I feel the same way I felt when I was 25."

So after just two days of being "hung up" on turning the big 4-0, "I think my clock is going backwards," he says. "I think I'm 39½ now."