Great Idea Tim!!
Ok, let me chime in here about Tai Chi.
I've been taking a class for nearly 3 years. When I attended the first one I thought it was almost a joke. How could this stuff POSSIBLY have any impact on my body???? Very unlike traditional exercise. I was sooooo WRONG.
I highly recommend it for anyone who has a class available.
Calorie wise, from what I have found the it's similar to walking. You can practice anywhere. No equipment needed. The gentle stretching and flexing of joints is awesome. Good for anyone, in shape or not. Warning. Much more challenging than it initially appears but do-able for anyone. Excellent start for someone out of shape and looking just to get started moving too.