Have you seen this?
At first it may seem a little strange, but it does address one neglected aspect of exercise prescription: It must be fun.
As I have mentioned before, the best designed program in the world will not work if you can not do it, but also enjoy it. Unless you are incredibly motivated you are not going to do an exercise program that you do not enjoy, so this is a great idea.
One day we could go on the net and have a game of virtual tennis, soccer etc as our exercise – as long as it was realistic it would be fun I think.