The choice of personal trainer, the variety of exercises and the challenge to do the best you can during a range of stretching and strengthening exercises. It focuses on arms, legs, abs, cardio, and total body coordination and flexibility. I scheduled myself to do the 9 week program at a medium difficulty and it has been a really terrific and FUN workout each and every time! I even took it with me on vacation and used it to workout whenever I felt like doing something fun. On the day that I wasn't scheduled to workout I went for an hour long walk with my husband and dog. I marked it down on my online journal and felt great about getting in that extra exercise. I hope I can keep this up, I feel it all over and I can't wait to see some results!