I've been reading a bit more fiction lately (Asimov's Foundation and A Confederacy of Dunces are the most recent). I am finding it very engaging, after a period of reading quite a lot of quite earnest non-fiction.
Two things I have have particularly enjoyed. Firstly, the lightness and humour woven through the stories I have been reading, even while dealing with quite complicated or difficult things. This contrasts with the often endless seriousness of non-fiction. An (obvious) reminder that jokes are good.
Secondly, all too often non-fiction books consist of a compelling first 60 pages, followed by 200 or so pages of reiteration and exemplification. By contrast, (good) fiction builds throughout, so the final pages turn themselves. I'm not sure if the lesson there is that non-fiction should be more confidently succinct, or that writers should hold a little more back for the end, if they can.
Either way, if you haven't done so recently, I recommend that you pick up a novel. And if you have any fiction recommendations, I would love to hear them.