Not for the faint of heart; no doubt excellent if you are young and have good building blocks re: your body. I crippled myself doing the lowest level for 4 days straight, this even while trying to modify the moves. If you have bad knees, hips, or ankles/feet, be very careful about doing this video. If you can repeatedly jump up and down on a hardwood floor, give it a go. Does get you pumping, but not worth it if you then have to stop doing anything but stretches for 2 weeks while your knees heal.