You don't have to carry a club or wear a bearskin to live like a caveman. To keep fit, a number of people have adopted the "Paleo" lifestyle -- eating and exercising like our ancestors from the Paleolithic era. Art De Vany, 73, is often called the "grandfather" of the Paleo movement. For De Vany, a workout includes pulling his Range Rover in his driveway. He compared it to "hauling heavy bison out of a pit." "If you think about it, you're using every single muscle in your body. You're not going to hurt yourself by overdoing repetitions," he said. "It's easy for me."