I thought I was in pretty good shape until I did this video. Jillian kicks butt! I did level one and boy, did I get a run for my money. This is pretty comprehensive in terms of a butt workout and I like how she incorporates yoga moves. Your core is also stimulated throughout level 1 (and probably the other levels too) so you get that added benefit. I can't wait to graduate to level 2. Really glad I bought this. The only thing I don't like is the need for hand weights...I need to get some but you can just use soup cans as a substitute.