Tom McCarthy's C, BTW, and so far it is excellent, and completely different from Remainder), and found that, over half an hour, I read the first few pages about eight times. It isn't that it wasn't interesting, it was that I couldn't concentrate. At all.
I didn't used to think this when I was younger, but I now believe that concentration is hard. And I am not one of those people who think that the distractions of modern life etc etc blah blah. I think human beings are naturally distractable. And that the act of reading a novel requires skills that have to be acquired in life, and can be temporarily lost.
Think about what a novel is asking us for: to switch off all of our perceptive organs and give ourselves over, entirely, to the consciousness of imaginary people. It is (as I suggested in the comments of the previous post) like sex. And who can blame us for not always being in the mood? Also like sex, it is a rare and transcendent pleasure, and one that gets all tangled up with our sense of ourselves. It's complicated.
Sometimes, when I have something I really really really want to read, like this McCarthy book, or a new Alice Munro story in the New Yorker, I have to wait until the perfect moment to read it, so that I don't blow it--ruin my experience of it with inadequate concentration. As a result, I occasionally forget to read these things entirely, while things I don't give a crap about, I dispatch right away.
And writing? Forget about it. These days, I can only write first thing in the morning. Anything past 9am, my mind has turned to garbage. Maybe someday I'll have to do my reading then, too. Until that time, it's catch as catch can.