To be honest, I can't imagine trying to remember to do exercises while sitting at a desk, not even during short breaks. It just doesn't work for me, when I concentrate, I sit still. If I were you I'd try to establish habits that ensure a little activity. Always use the stairs, just pretend the elevator isn't there (or tell yourself it's just for wimps ;-). Obviously, try to see if you can work out a semi-commute by bike or run. Is there anywhere safe you could park a suitable bike ride away, and ride in from there? Make an appointment with a friend for some exercise in your lunch break - but you do need to eat too.
I feel a little like that after every vacation, when I go from being reasonably active all day to sitting still for hours at a time. But it seems to even out because I work harder when I exercise. It can be a blast to get in a good workout in the morning, and come into work all hoppy-peppy and get to sit down and relax, with a nice cup of tea :-)
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett