Do you exercise?  If you're a writer, why not?  I'm serious.  Oh, yes, fine, authors aren't exactly known for their physical fitness, though Norman Mailer used to be boxer (but that was because he was an asshole and not a writer we should take seriously).

I run.  I run rather a lot.  I find it immensely helpful with writing.  It's rhythmic, meditative, and you don't have to talk to anyone, i.e. the perfect venue for solving plot problems, restructuring, fixing logic questions, etc, etc.  It's good for you, too, obviously, mitigating the widening of the rear end inevitable with hours in front of the computer.

Also, metaphysically (or perhaps, the exact opposite of metaphysically), I don't think it's a good thing for a writer to be too separate from their body.  Elsewise, how would you write with your gut, your heart, your blood, your libido?  If you're just writing with your brain, your book's going to be a chilly place.

Just finished Anne Enright's Booker winner The Gathering (which I have in non-Booker advertised first edition; I've been a fan for years now) and though I didn't find it as satisfying as, say, What Are You Like? it's still very much a novel written from the stomach and the gall.  Good stuff.  Next up, Jane Smiley's Ten Days in the Valley.