There’s a certain class of bodily actions that I feel especially grateful for, and that I’ve been noticing more and more recently. I’ll call them unconscious subroutines—little functions, procedures, or actions that your brain and body carry out with next to no involvement from your conscious self. I’m not talking about totally unconscious behaviors like your heartbeat, or the defenses of your immune system, although those are cool too. I’m talking about behaviors that are sort of...