Our brains like a challenge

Instead of outsourcing as much brain function as possible to technology, make a habit of challenging your brain during your routine daily endeavors. Replay your favorite song and try to memorize the lyrics, bust out your school yearbook and try to recall the names of your long-lost classmates, or add up numbers in your head instead of always relying on a calculator.

— The Primal Blueprint, Mark Sisson

This is something I can identify quite clearly. I enjoy trying to remember names from school and look them up on Facebook. Recall is a fun thing to do!