Last night I left my class and discovered that my step counter had tallied 6000 steps during those 3 hours. This struck me as a little nuts: how could I have walked >2 miles in that time? I do pace slowly as I'm lecturing, and I circulate during group activities to see how everybody's doing. And I gesticulate whenever I'm talking, apparently with enough enthusiasm to make the little accelerometer at my wrist think I'm race-walking to Nebraska.
I assumed it was a fluke, and then I looked at it again before and after my 50-minute class today: 3000 steps.
Maybe that's why I'm so tired. Or maybe it's the time change. Or maybe it's the cold Stella shared with me. In any case, I'm calling it a night.