Aside from programming, what are your hobbies? Mine are:

1) American civil war. I have about a hundred books on the subject, mostly focusing on military aspects, strategy and tactics, campaigns and battles.

2) Mathematics books (not textbooks) which are aimed at people who have done at least a year of the subject at university. The books of Paul Nahin are good examples.

3) History of science. It's a far messier (and hence more interesting) subject than you might glean from TV documentaries or popular books.

4) Hiking in remote mountainous areas. Solitude and nature, a great combination.