When I get like that I either take a nap or tidy up my sewing area (and basement). Then when I'm rested and feeling like sewing, the area is allllll cleared up and ready to go!
Maybe it's the body/mind telling you that you need a rest.
E.T.A. retail therapy works but it can be horribly addicting and bad on the checkbook.
I love your definition of "FINISHED" Love it!