But with that being said, winding anecdote: Last month I was helping my folks clear old boxes that pretty much contained my entire childhood. Aside from 3 books there was nothing I'd remotely thought about keeping for well over a decade and I was happy to give or throw away whatever I found. Old toy cars, action figures, way too many PS2 cheat book and magazines to count, I had no connection to anything as we sorted out charity deposits.
I'll admit the Lego was a fun nightmare (I admit that I never should've opened the box!), I'm still scrounging through a mountain of bricks putting together which sets I can, but I won't be keeping this myself.
But then there was a box containing a wooden train set.
The last time I saw it I was ~4 years old. And there I was, looking at something so innocent that hadn't crossed my mind in over 20 years and I immediately broke down in tears on the spot. It felt raw and even thinking about it is still overwhelming. I was laughing with tears streaming down my face as I talked to my mum about it, and even though I won't touch it ever again, I can't help but feel thankful that she decided to keep it for me.
I wish I could make some poignant point about memory and the human condition, but it's weird and odd the way we can have such different emotional attachments to things, and don't take it too hard if some things are too hard to throw away.
The last time I really tried to declutter felt great. I had a big box of Goosebumps and Animorphs books that I loved as a kid. I loaded them up in my car and drove around to all the Little Free Libraries. I hope some kids had as much fun reading them as I did.
I have a whole bunch of books I'm never going to read gathering dust on my bookshelf, and I've only really noticed them now that you've said that. Thanks for the reminder!
As much as I couldn't part with the wooden train set, it's a lovely feeling sharing something you once loved. When it came to all my childhood books we found a local teacher who was more than happy to come around and take them off our hands.
Like, put the stuff in a box, slap "throw away before X" date on it. Take any stuff that you need now, on real need, out of it, anything left goes to trash after the date.
If I was you I would look to getting rid of other things so you can keep your books or I would impose some artificial rule like "if I haven't read 10 or more pages in 3 years the book has to go."