04/18/2012 at 12:45 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
"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."
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.