As for all of the stuff that's still in boxes, you obviously don't need or want to use any of it, so why not just take it straight to a charity shop without unpacking it? No chance of sentimentality getting in the way then.
Oh my god I hear you - I do - but when I read your idea I cramped up. I've become very stuck mentally with regards to my things. I was not like this when I was younger. Then again, I never had to darn much back then either. You're right though. I know that in essence you are right.
I have heard of the 30 day minimalisation game. Does it start small and work up though? I think it does and that always seemed weird to me. I felt it should start big and then wind down because with each day surely it's harder to find things to get rid of.