I feel powerful and youthful in my perfectly healed and healthy body.

Youthfulness is not really about the year on the birth certificate. Watch a seventy-year-old learn to sail badly and enthusiastically, then watch a twenty-eight-year-old who has already decided what they are not the type to do.

The measurable version is recovery time, and that answers to sleep and to use more than it answers to age. The unmeasurable version is willingness — how quickly you conclude that something is not for you.

Only one of those is available to you this week, and it is not the one in the mirror.