Urination break, I assume you go to the toilet :P Jump in a cubicle and do your push-ups against the wall really quick. Not as good as doing them on the floor but still gets you going. Squats can be done too. Just don't make too much noise from the exertion, people might get the wrong idea. A friend of mine before used to do the pushups against the wall, (not necessarily in the bathroom) and they are pretty helpful : )

I stare at the computer all day, sometimes I work through lunch or only have 30 mins of lunch. What do I do when I come home,had dinner and my daughter is asleep? Either TV or Computer or Smart phone, sometimes a book. You would think after sitting on the computer all day at work I would want a break from it. There is an easy way to do this, don't turn the computer and go to bed early. Then get up early. Then go for a walk early, at least 40 minutes or more. If you get up early enough this won't impact on your day. You are just transferring the time you would spend at night reading Slashdot and getting tired to the morning when you are re-energizing your body. Improving diet is necessary too. My brother has been doing this for months now and he has been able to lose a lot of weight. He is fortunate working in a lab in that a good part of the day he is expected to stand up. I will see how I go trying to make this change myself. Its not easy because I love to sleep in...probably because I love to stay up late (on the computer:P )