The 39-year-old singer said she has to work out because she "loves to eat", reported E!Online.
"Find your local gym and get into different classes. That makes it exciting (and) you're doing new moves. You don't even realise you're working out it because you're focusing on 'How do I get this right?' But you're having to control muscles so it's making you sweat.
"Keep it interesting... I have (to do) treadmill, elliptical, bike and dance. I do the bands - I do it all. I have to work out because I love to eat - I had two Double-Doubles last weekend!," she said.