Nick Cannon says wife Mariah Carey is focused on getting back her 'knock out' pre-pregnancy body.

Nick and Mariah welcomed twins Moroccan Scott and Monroe Cannon in May. Mariah, who is famed for her enviable curves, is absolutely intent on getting back into shape as soon as possible.

"She's so focused right now on every aspect. She's going to come back and knock out the world," Nick told Us Weekly Wednesday at the America's Got Talent finale in Los Angeles. "She's getting in shape."

Mariah hit the gym almost immediately after the twins were born. Nick is impressed with his wife's progress. He thinks that Mariah may look better than ever when she reaches her fitness goals.

"At two months she was walking around in a bathing suit. Every day she's just killing it,' Nick declared.

' personally think she's going to come out looking better -- looking like it's 1990! I think that's what she's aiming for, and I think she'll reach that goal."

Mariah is doing exceptionally well with her workouts, but she and Nick only exercise together occasionally. Nick simply can't keep up with his wife's rigorous fitness routines.

"We do, but she's too serious!" Nick said. "She works out in the water. I don't like the water. I can't swim that well."