Back away from the keyboard! Personally I go out to the shop and work on a fabrication project. Go out and split some wood, or take the recumbent trike out on a ride. About anything to shake the brain lock causing the writer's block and relax my mind! A good jigger of bourbon, with a good cigar sitting on the porch after the night critters come out to sing! Next thing I know, I'm back on track!
Go and do something completely different for a while. Find that something other than writing that challenges you a little bit. Shake it up a little bit, something that requires your attention to do!