Gunnar Peterson celebrates Fitness Month

Celebrity trainer Gunnar Peterson has worked with actor Nick Cannon to build lean muscle. Chris Weeks/Getty Images

To celebrate National Physical Fitness Month, celebrity trainer Gunnar Peterson has launched The Gunnar Challenge to allow everyday people to achieve fitness and weight loss results.

Peterson has worked with Kim Kardashian, Jennifer Lopez, Nick Cannon, Terrell Owens and Sylvester Stallone, among his many celebrity clients. And the stars are like anyone else, Peterson said.

"Two arms, two legs, a torso and a head," he said. "They are using the best of what they have to create a better quality of life."

Registration is open now at gunnarchallenge.com, and the first challenge begins May 21.

And Peterson, who has 25 years of training experience, is challenging anyone who says they don't need help to get in shape.

"Would you strap on a scuba tank and go off the back of the boat without someone else there? Like in tennis, you're not just playing with your friends. You are working with a pro and getting more out of that hour," Peterson said. "There will be accountability and motivation. You will get fired up and enjoy it."