Personal
When I am not actively thinking about research, I enjoy solving puzzles, especially those with mathematical and/or linguistics flavor.
This is largely a remnant hobby from high-school days of participating in national math, physics, and astronomy olympiad training camps (which, although I did not manage to secure a spot on the national teams in either, remains one of my favorite experiences in life).
At other times, I get a kick out of reading about and discussing cosmology and physics in general.
This is largely a consequence of being the only son of two physics professors.
Though a good fraction of our conversations drift and end the same way.