I've been thinking lately that it would be interesting to ask people what else they do other than writing that's hugely significant in their lives. Also, does it in any way relate to your writing (it doesn't have to)?
Personally, in addition to writing I've been doing a certain amount of bass guitar playing lately-mostly in church, to be honest. The church I go to has no organ and thus has a variety of rotating all volunteer groups that play. Some of them are more focussed on a particular theme than others. For example, I play in the Guitarchestra. It ranges from 8-20 people playing guitars, mandolins, basses (guitar and double bass), and (often) an accordion.
I've been learning how to play a fretless bass lately which is different from a normal bass guitar in that the lack of frets allows you options in playing a note that a fretted bass does not.
It also allows you to slowly (or quickly) go out of tune in a way that's simply impossible on a fretted bass.
So that's a bit of a learning experience.
At points in the past, I've also been involved in long distance running, and the martial arts. Most of my experience in the martial arts is with Tae Kwon Do, though I know a little bit of aikido, and a Filipino stick-fighting style.
Honestly, I'm not sure if any of these affect or apply to my writing except in terms of background knowledge, and a general sense of how entertaining people with music is similar and different to writing.