Mariah Carey: How I Got My Body Back After Baby

By Mike Fleeman

04/19/2012 at 07:15 PM EDT

Showing off her tight midriff, Mariah Carey reveals that getting back into shape after giving birth to twins has meant more than going to the gym.

"I realize that 90 percent of losing weight is my diet," Carey, 43, who promotes the Jenny Craig plan, says in the May issue of Shape magazine.

"Today my workout routine is more about getting and staying toned," she says. "And for me, that means either taking hour-long walks a few times a week or jumping in the pool three or four days a week to do 45 minutes of aquatic exercises."

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As for her husband Nick Cannon's health scare – he was hospitalized for a lupus-like autoimmune disease and kidney failure – Carey says, "It was really frightening, but he's feeling much stronger."

"He's taking better care of himself, eating a diet low in sodium and sugar, and getting more sleep," she says.