I was using the Firm and changed my satellite provider. My new provider offered FitTV. I watched, but most of the workouts were only a half hour long, and after using the Firm, I knew I needed to work out longer to maintain, much less progress.
One day, I found some workouts (Cathe) that took up the whole hour of TV (with commercials, it's shorter), so I taped a couple and tried them.
Wow! I was hooked, and have since bought almost all of her workouts and learned about other advanced instructors from this forum. When I first started, I had to use the commercials to catch my breath so I could finish, and when the day came that I needed to fast forward, I knew I had to start buying my own. Then, it took more time to get through the whole length of the workouts with no commercials.
Now, I can do most of her workouts all the way through without modifying too much (except weight). I haven't lost much weight, but I am much more healthy and look much better than ever in my whole life - and I'm 45.