[daeken]

For the last month and a half, I've been using a treadmill desk for 1-3 hours every day. I walk at 2mph (a nice slow pace I can do consistently without thinking) and it's been absolutely fantastic. It doesn't make reading or typing difficult (the desk is well-stabilized and my Thunderbolt display is on a very heavy arm), and I'm down nearly 25lbs since I started, thanks to a combination of diet and exercise.

I truly can't recommend a treadmill desk enough.

Edit: You can see my setup (sans laptop) here: http://imgur.com/Jqfy8eG