Whenever I take a long car ride I end up exhausted afterwards, and I'm always like "why am I so tired? I was just sitting around doing nothing all day."
But the answer, it turns out, is I was doing something. Riding in a car jars your body in many directions and requires constant microadjustments of your muscles just to stay in place and hold your normal posture. Because you're inside the car, inside the situation, it's easy not to notice all the extra work you're doing just to maintain the status quo.
There's all sorts of work that we think of as "free" that require spending energy: concentrating, making decisions, managing anxiety, maintaining hypervigilance in an unfriendly environment, dealing with stereotype threat, processing a lot of sensory input, repairing skin cells damaged by sun exposure, trying to stay warm in a cold room.
The next time you think you're tired from "nothing", consider instead that you're probably in situation where you're doing a lot of unnoticed extra work just to stay in place.
