When I can no longer see my desk under mounds of mail and paper, I have a terrible habit of just tossing everything into a box to "deal with later". Today, I set the shredder and a trash can next to the file cabinet and forced myself to go thru about 3 stationary sized boxes (about 6 months worth). I got it all down to less than a shoe box of stuff I do actually have to deal with.
Then I went out to my car and pulled every last thing out of my glove box and sorted thru that. Now that it isn't filled with fourteen years of insurance cars and receipts for oil changes, I can actually put useful stuff in there!