Find a Little Free Library and leave some good books you don’t plan on reading or rereading soon. Every city should have these. Benefit of this is that karma works and someone else will usually leave something nice.
If I was running one, I'd have maybe 10x what will fit in it, and constantly rotate them. The ones that don't move within a couple months go to the thrift store.
P.S. the books I add are scifi. They never last more than a week :-)
That's how I run mine. About twice a week I rotate ~10 books. Either ones that have been there for longer or ones that I know will never be taken anyway. (I leave everything for at least a week, but the 'guide to 2004 Honda Civic maintenance' never stood a chance...)
Every once in a while I sort through my 'additional collection' that I keep inside my house and take the unattractive ones to the thrift store.