Get rid of anything challenge
I know it's not very specific, but hey! It leaves it open. I just gave away gardening books that have been sitting in the car for eons. Now I am getting up the motivation to call the thrift shop to come take away a set of sofas and a chest of drawers that are cluttering up space.
I also challenge myself to get rid of a notebook of garden clippings that I lost interest in, my entire Little House on the Prairie taped episode collection, and a bunch of other stuff in boxes I've targeted for removal but haven't done anything with. Any other self-challengers out there?