Every book you actually finish leaves a few sentences in your head that stick around for years.

Finishing is what makes anything stick. Books you abandon leave nothing at all, while the ones you see through tend to deposit three or four sentences somewhere permanent, and those lines come back years later in situations nobody could have predicted.

So pick something you actually want to read rather than something you think you should, and get to the end of it. Keep a page at the back for the lines that land, copied out by hand. A year from now that page will be worth more than any summary of the book.