When I watch the tv, every time a commercial comes on I get up and clean something. Show comes back on...sit back down... commercial...up and clean something. ;)
I used to do the same with physical fitness! Every commercial break I would do crunches, pushups, or pullups...alternating through all three. And every fourth commercial break I would "rest" by cleaning or doing some other chore.
It also resulted in a more enjoyable TV viewing experience because I'd get the blood flowing every 10 mins or so and I paid much better attention.
Here is one I used to do when I was home. I would have two gallon water jugs and a heavy box. Commercial comes on I curl the two jugs for a minute, push the box for a minute then do sit ups until the show came back on.