Just to add to what others are saying, some books are written in a way that very much "speeds" you through the text, and the books you're mentioning are pretty intellectually dense. Reading for "fun" means different things to me depending on how I'm feeling. If I'm stressed or tired, but I still want to read, I need something that fits the bill. 1984 is something my brain will want to chew over, so it's more of a fit for when my brain is feeling frisky. I'm very much a person that needs to pick media that fits my mood, or I'll have a miserable experience when I might otherwise be reading my new favorite book. If I find I can't get into a book no matter how much I think I want to, I take it as a sign to just put the book away for now. I've had a lot of success just moving on to something else, and coming back to "problem" novels later.