J.P.
I put a used box under my desk to put my feet up on, it was a lot nicer that way for me. Also having a comforatable chair is important. They make these swayback, back supporter that goes in a chair to support the back....or a firm pillow would work too. Lots of water and trying to get up for that walk is the best medicine I found to work. I only worked until my 8th month, but what you are doing now is what carried me through in my office.