we have several people here who bring tennis shoes and walk the building during lunch/breaks/first thing in the morning (perhaps they do it at the end of the day, too)

We just began 4 day work weeks for the summer, I'm here at 630 and brought my yoga mat - did a few rounds of sun salutations to begin my day - I would be uncomfortable if there were lots of people around when I did it, but because it's so early, I go for it
Modified CG since Dec 2011