I'm on a computer all day at work and the bulk of my activities at home are computer-based as well. I've been able to get into a nice habit of taking daily walks, usually right when I get home from work (before even going in the door). It's quite enjoyable and sometimes I end up wandering around for miles/hours before some other motivation urges me home. Just being in a place where things can be >100 feet away feels novel most of the time. Computer usage is bizarrely user-centric, compared with the outside world; a contrast that shouldn't feel as profound as it does.

I started off just thinking of walking as a simple cure for fogginess/tunnel vision/vague anxiety, but it's grown into a subconscious urge. Also, I recommend avoiding music or other audio media.