I bought this DVD a few weeks ago because I hate running during the summer when it's a million degrees out. It has over 300 reviews on Amazon with a 5-star average, so I thought I'd try it. These workouts are 20 minutes each, but very challenging. After day one, I could barely move, I was so sore. Within a few days, I could really notice a change in my muscle tone and my energy level increased. I think I've found my favorite workout for the summer. Running never gave me results like this!