When reading a book, it's super difficult for me to retain the information within. I have really bad working memory problems in general, and reading is just one area where those problems manifest. With reading, though, it's particularly disappointing, because reading is a form of entertainment – a form of entertainment that's good for the soul – and I want to be able to enjoy it fully.
I can read a paragraph twice, thrice, four times, and still not be able to recount to you what I just read. Eventually, I just move on: If whatever was in that paragraph turns out to have been important, I tell myself, I'll come back to it again later. I'd like to keep at least something from every paragraph, but sometimes I just have to throw the thing overboard so that I can get on with the story.
However, maybe that's a good place to start improving: with a goal of keeping something – just one piece of information – from each paragraph, before moving on to the next. That's better than nothing, and my brain may get better at prioritizing information, which is probably one of the things it's currently failing to do when reading.