BROOK: On a family vacation the week before starting college, I nearly drowned snorkeling. My mask broke in shallow water and I stood up in a bed of sea urchins. With each desperate step their needles filled my feet with unbearable pain; it got so bad that I couldn’t use my legs to kick. I held my mask with one hand, leaving me just one arm to paddle. The sixty feet to shore felt like a mile. I made it out of the water but spent the first weeks of college limping on swollen feet. And I developed a dim view of snorkeling.

JILL: The inside of the plane was roughly the size of a sports car, only imagine one where all comforts have been stripped out, leaving nothing but a dirty aluminum floor and vibrating walls. I was crammed in there with the pilot, my tandem-skydiving partner, and a barefoot guy with a GoPro strapped to his head. In the years my instructor had been making jumps, he said, he could count on one hand the number of clients who looked as frightened as I did.