A lot of racers work in offices and even more talk about fitness both during and outside of the race season.
I spend 9 hours a day in an office, a majority of which is on conference calls. A few things I do which others might consider are:
ankle weights. a set of 10lb ankle weights make great exercise just doing a few leg lifts, or roaming to the coffee machine and back.
hand exercisers: I go through 2-3 of the STIFF exercise balls a year. I switched to a silicone block which is for climbers and that has lasted much longer. This is great to take into meetings too.
weight ball: I picked this puppy up yesterday and walked around in the mall for 6 hours, tossing it from hand to hand. My arms were shot when I left.http://www.sportsauthority.com/product/index.jsp?productId=2161015&cp=2057738.702281.694015&parentPage=family
I only got the 6lb ball as they didn't have a 10lb'er, but will go out looking for the 10 now.
It's a bit larger than a softball and works fine for tossing a foot or two in the air and catching again.
Stupid little things that can and WILL make a difference in your racing if you lead a sedentary lifestyle of a cube-rat.