Through the joys of expensive real estate I don't have the luxury of separate rooms but personally I've never found it that important. I have a desk that is almost exclusively used for work that seems to fill the role, but even that is more for ergonomic reasons than anything. I feel the social isolation others mention, but that's solved with more regular nightly visits to the pub.

The big thing I need to improve on is simply getting outside more and going for walks during the day. A significant part of my commute was walking and now that's gone.