I admit to doing shoulder rolls and arm stretches. And if I'm about to doze off, I run the stairs. My office is in 3 story building and one of the staircases is close to my office. Run down, run up, down, up. Back to desk. Log back onto computer. I find it more stimulating than raiding the vending machines that happen to be in an alcove next to the staircase.

And when it isn't gawd-awful hot outside, there's a walking track outside. A group of us will go "strolling". Sometimes at a stroll, sometimes at a brisk pace. But strolling is no fun when you break into a sweat just by walking out the door.