I have a secret to getting a free workout. I rent execise DVD's from my local library. Every week I pick up 1 or 2 DVD's and try to pick ones that are a little different. This way, I never get the same workout twice and my body has to keep guessing, which is good for the metabolism.
I have rented DVD's on Walking Off the Pounds, kickboxing, low-impact aerobics, dancing, Pilates, yoga and varieties on each of these. It keeps me from getting bored with my routine.
It's also a great way to try a DVD before you buy it. You may not realize you enjoy yoga until you try it. Personally, I found that I enjoy kickboxing and yoga the most. So I was able to purchase those, knowing I would get more use out of them.