As an exchange student in Tokyo, I joined the university judo team and spent my first week at the dojo flinging myself to the mat, learning how to fall without getting hurt.

The sound of a fall is important. A well-executed one sounds like a hundred-pound bag of sand hitting wet pavement: a single, heavy smack. That means that all important body parts have hit at once, absorbing the shock equally. But a fall that starts with a thud, immediately echoed by limbs hitting the floor, means someone is in pain.