Occasionally I use Flylady's "27 thing fling boogie" and get rid of 27 things at once. I start with obvious trash. (I count a handful of trash as 1 thing, not every scrap of fabric, pin, or wad of thread.) Then I find things to donate. When I get to 27, I pat myself on the back. Sometimes it's enough momentum to keep going; other times it puts the needed brakes on overwhelm. Either way, it's another smart game I play when I don't know where to start.
Oh, and I move clockwise around the room so I can see where I've been. Visual progress is motivational.