Get Kelly Rowland's abs

But a stomach like that doesn't come easy.

"It takes hard work to look like this — and even more work to keep looking like it," she told Zest. "I practice yoga, which really helps me tone up."

"I also go to the gym to do some cardio a couple of times a week. I particularly like the bike and cross trainer."

Kelly also said she owed her super-flat stomach to 200 sit-ups before bed, whenever she can — ouch!

And when it comes to diet, kelly follows the 80/20 rule. "Most of what I eat is healthy — fruit and veg, grilled fish and meat," she said. "But 20 percent is whatever I want."

Watch the video above to see Kelly's ab-busting moves!