Yeah, but my daily work is making images. For me, using my brain differently - for chess, for example - is entertainment. I am not looking to get better at it, necessarily; I don't compete, or mind that much if I lose, but I do like to play and talk about it.I consider entertainment anything that lets me not use my brain, which was entertainment's original intent, a distraction from the daily woes, from the plauges of the world (Literally) and from the minutia of ones daily work tasks. It has of course evolved and what you find entertainment may make your brain work, but I find I focus on my jobs better when I don't stress the old supercomputer too much.
YMMV.
(Edit: Oh, and I'm a bit disturbed by the notion that you can only be entertained if you turn your brain off..)
I am in complete agreement with the comment in the edit. I've never been entertained by allowing or being forced to shut my brain off, it could be adequately described as a state of frustration to do so

Wargames are entertainment, chess is entertainment, excellent literature is entertainment, analytical and continental philosphical works are entertainment, classical philosophy is entertainment, history is entertainment... people should view intellectual investment as a means of entertainment and ultimate enrichment, not a chore.