I was trying to read a fanfic today, and struggling with the awareness that my brain isn't up to reading fic that's this good and deserves this much careful reading and absorbing. Not if I want said brain to do anything else for the next day or so. I love reading, but words on a page have become a trial for me - a physical and intellectual chore that reminds me painfully of how capable I used to be, and still can be on those very rare and unpredictable 'good days'. I had one when Terry Pratchett's "I Shall Wear Midnight" turned up on the Kindle, and just devoured it.
Normally, though, reading that requires thought and memory and attention to detail just isn't worth it, along with most of the novels and fanfics that I pick up and put down again with a wistful sigh.
Going to finish this one if it kills me (or my brain and prospects of functioning for a few days, anyway):
How Not To Fly by Toomuchplor - Post-series SGA Sheppard & McKay slash, real life biting Sheppard hard. It's a fic that deserves readers with functioning brains.