A lot of people love Thrill of the Fight for exercise. It's funny because it isn't really directed exercise, it's a boxing sim. You can take it slow but the game makes you feel like you have no choice but to punch for your life. It gets you really worked up.

I actually ended up with a bit of repetitive strain from throwing hooks and had to switch to Supernatural. It's a monthly fee but it's more purpose-built for exercise.