Nichols said Waters gradually changed her body, making her stronger and more toned -- "Valerie doesn't believe in working out for two hours; misery is not the way" -- and teaching her how to eat and enjoy fitness, so that she now plays tennis and does Pilates on her own.
"Regular people can do her program and change their body," said Nichols, who added nearly 15 pounds of muscle for her role in "GI Joe," before returning to her long and lean look. "It will work for everyone, without putting them through hell, without making them dread it. It's very accessible and user friendly."
New York Times cultural writer Robin Pogrebin, who got a "sampling" of a workout with Anderson, said she can see how having to do multiple repetitions of arms, leg and abdominal exercises every day could be tough. Anderson's DVDs on the other hand "a regular person can do," once the person can follow the sometimes intricate dance combos.
She gets the appeal of celebrities and their trainers. "We are a culture just craving a recipe for success," Pogrebin said. "That's why diet books sell and workout DVDs are always going to have an audience."