I absolutely LOVE this workout! I did it 30 days in a row, but I had to work up to it. The first time I did it, I could hardly walk for a week! I think I did it 3 times before I was ready to do it everyday. After doing it a few times, I was no longer in agony the next day. I am a big fan of Billy Blanks' Tae Bo tapes, and I was shocked to discover that I work up a much better sweat in 25 minutes with the 30 Day Shred than I did in 60 minutes of Tae Bo! The moves are really easy to follow too (no choreography). I've lost 7 pounds in the 5 weeks since I've been doing this workout, and I definitely see a big difference in muscle tone. (I started out about 45 pounds overweight.) Let me warn you - you will absolutely want to kill Jillian while you are working out!! She is impossibly tough! This workout is not for absolute beginners, but if you are able to do jumping jacks, you can definitely handle Level 1. If you have problems with your knees, don't bother with this DVD. I'm struggling with Levels 2 and 3, but I enjoy the challenge. I love that you can choose what Level you want to do on any given day (once you work up to it) because it gives you a much better variety than doing the same workout every day. I think what surprised me the most about this workout is how FAST it goes by!! I recommended this workout to a friend of mine, and she is loving it too. For me, this workout was well worth the money!!