The basic idea goes that you have to satisfy those at the bottom before the top: if you’re freezing cold and hungry, you’re not giving much thought to the joy mastering new skills. Not terribly robust. But interesting and somewhat clarifying.

See updated sketchplanation of Maslow's hierarchy of needs.

Maslow’s Hierarchy of needs

A mnemonic that has helped me many times.

Repair injured joints

In temperate latitudes and around the Summer. 12 minutes per finger. 1 hour for your fist. (hat tip to Joel Wilson)

Rules of thumb for remaining daylight