I've been impressed by how effective the petite 20-something blonde trainers are in encouraging middle-aged men to push to their limits during their 5 am work-outs at my gym. (I suspect the healthy-looking male trainers have a similar impact on the ladies.)
That should be no surprise, of course, given male psychology. Gyms and blonde trainers don't come cheap, however.
Even before Paul Ryan touted his enthusiasm for the Insanity program, I had been hearing about it from people (Ryan uses Insanity and P90X). I kinda like the way the woman in the Insanity ad says "I want to feel good about sharing myself with my husband for many years to come." That's a great attitude.
The problem with home work-out regimens is the self-discipline. On the other hand, challenges to self-discipline are how we build character. But, on the other hand...