At a certain point as a developer, you begin to hit a plateau, where new
concepts or techniques no longer produce the drastic increases in
productivity you once experienced (such as the realization that you can
do most of your job with a handful of well-written shell scripts).
You could learn a few more Vim tricks, or finally get around to learning
Ruby. But there’s one thing that most developers don’t pursue, yet is
beneficial in both programming and non-programming pursuits: