Dancing Dolphin is so right: it's kickboxing modified for, you know, normal people. It's actually not that hard to do, but any workout, including walking, is serious if you just keep at it. There are a lot of stretches, punches, kicks --no flying through the air or wild stuff -- and he's good about explaining how to do the moves, doing them more slowly, and then speeding up necessary. You might go to his website -- typing in Billy Blanks works fine -- and you can see demonstrations of his routines. It's like everything else, though: you need to find that fit where you think yes! this is me. I have friends who do yoga and I like it and have done it, but I think I get better stress relief by kicking and punching....