I've read about it, but I haven't read it - there's quite a waiting list for it at the library! =) I love the principle of keeping only the things that spark joy. Actually, I tend to err on the side of ruthlessness when it comes to simplifying my stuff, and on the side of procrastination when it comes to acquiring things. W- will attest to the ease with which I set aside things for donation, and I've let go of lots of books, clothes, gifts, and other things. In fact, I think I might improve by being a little more like him - he keeps quality stuff around for years and takes good care of it, even if it's infrequently used, and sometimes these things turn out to be surprisingly handy.

(Also, from what I've seen of Kondo's book: such prettily organized drawers! Something to experiment with.)

Stuff in my mind, now, there's an interesting challenge. I'm mostly good at hanging on to just what gives me joy and at letting go instead of feeling guilty about incomplete things, but there's room for improvement. =) Possibly tied in with what I've been thinking and learning about Zettelkasten and other systems for managing small chunks of info. I think my ideal mental organization (which combines stuff in my head, in my files, on my blog, and in other digital archives) would result in the feelings of "Ah, here's where that fits and how it relates to other things. Let me pull out this chunk so that I can work with it more, and then I can put it away neatly." Hmm...