I heard this interesting interview yesterday on NPR. I don't agree with everything Reynolds said in it, but a lot of the info is very good.

I'm incorporating the idea of standing up every 20 minutes--hopefully walking around when I do, but that will depend on energy. I'm at least going to stand for 2 minutes. I found a great computer timer that I can set for 20 mins. I'm just amazed at how quickly 20 mins goes by. I thought I was getting up from my chair much more frequently than I am!

Stand Up, Walk Around, Even Just For '20 Minutes' : NPR