Building things
Outside of client and employer work, I build small personal projects for the same reason a lot of engineers do: to try an idea end to end without waiting on anyone else's roadmap. This site and its public reference repositories are part of that habit.
Traveling
I like traveling when time and work allow it -- new places are a good forcing function to slow down and pay attention.
Learning Spanish
I speak conversational Spanish and keep working on it. It comes up more often than people expect, both while traveling and at work.
Family
Time with family is where the rest of this stays in perspective.