This is a killer workout. I made it 10 days with level 1 and 3 days with level 2 before having to stop. My knees are killing me; I could barely walk afterwards. Sweat like a pig and no weight loss or inch loss. Will probably need a very strict diet to see any results.Jillian is very pleasant to listen to and very motivational. I believe in her workouts... just not for anyone with knee issues. If you are young, strong, can take constant pounding on the knees, then this workout will do you good. It is a challenge and a very difficult workout. But if you have any issues with high-impact workouts, or workouts that are killer on your knees, then avoid this one.