Well there’s your problem!
Waking up this morning was not the best of all possible experiences. My hips and my back hurt quite a bit, and I was more than a little peeved with the black ball of fluff who started insisting it was time for breakfast sometime around 3:45. I finally appeased the felines around 6:30, and discovered that walking was requiring both effort and thought, and that even when given plenty of both, the process was still both slow and unpleasant.
After I got home from dropping G off at the bus, I went through my usual morning pre-computer routine.1 This time, I also grabbed a couple of ice packs.2
Thus supplied for the morning, I hobbled downstairs, and went to set up my laptop.3 It was at this point that I realized that the power cord for said laptop was still upstairs, in my carryon.