I'm not a fan of mixing exercise and office work. You won't be seeing me on one of those goofy-ass desk treadmills.
Use your lunch hour. You can eat in 15 minutes. That leaves 45 to do something meaningful. If your office has a gym, it's pretty easy. Otherwise, head outdoors and get some cardio.
Good advice, though I was thinking more along the lines of stretching or exercises one can do while sitting at their desk to avoid remaining stagnant for too long.
I usually take a 30 minute walk on my lunch break and try to get up and move around every hour or so.
I also run after work or go to the gym. Just try to be as active as possible.
When I was "chained to the desk," I set a timer to go off every hour. Then I got up, and took a walk around the office space. My office was open plan, with a corridor between cubicles that ran around the floor. About a five minute walk every hour.
I found this site helpful
This shows up under a search for office. http://darebee.com/wods.html#name=office&page=1
Personally I'm working through the startup program called foundation. http://darebee.com/programs/foundation-program.html
They all are theme workouts and it's free. The body weight exercises can be done most places.