Ah, time … what even is that? Like you, I spend a lot of my time outside of job on my comic, including content creation (illustrations, pages), the networking, the promotion, etc. I recently cut back on time spent on comics (it was over 20 hours a week, outside of a full-time job) to allow for some other projects so I wasn't putting all my eggs in one basket … so to speak. Other major projects in the works are a novel ready to launch this month, and a secret fashion/style project I am working on launching in April or May. I also believe in good food and good rest -- I never short myself on sleep, and unfortunately I am one of those that could sleep forever.
Other than that, I play games, read books and comics (usually webcomics), study languages, do random freelancing/ concept arts, spend time outside, dance, and maybe stare at walls.
The staring at walls is necessary recuperation time, you see.
I think it'd be neat to play more instruments. I would like to learn the accordion. But in all honesty, I think if I had more free time, I would devote more of it back into the comic.