“Everything teaches a lesson.” I was feeling disappointed and anxious in the days following an ill-advised wrestling match and concussion. It was the end of a summer spent working at a boy’s camp, and my plans to lead a culminating backpacking trip were now in doubt. My head buzzed with headache if I tried to read, listen to music, or raise my voice. “Everything teaches a lesson.” These were my friend Nemo’s words of consolation. I don’t want lessons — I want to be healthy, to go on this trip, to be able to do everything I enjoy, I thought through tears. His consolation was spotless in its truth and logic, yet, in the moment, unable to console me at all. I’ve now learned that the average concussion heals in two weeks; my concussion experience was not an average one. There are various reasons for this — whiplash, hypochondria, poor management. But what matters is that, over the next three months, instead of recovering, my condition declined. The list of stim...