This prompt from Long and Short Reviews was fairly easy, because when I'm not feeling well I read stuff that requires very little thought - mostly romance. It's not something I read a lot of, but when I'm sick I like to disappear into that world, and these are the sorts of things that help me do that.
The Time Traveler's Wife. It may not make a huge amount of sense, but I find it to be good escapism.
To Marry A Prince. This was the first romance novel I ever read, and it's perfect. It had a great, strong heroine, an equally great best friend and a central romance you root for all the way.
Anything by Anne O'Brien. She writes more at the romantic end of history and I've loved every one of her books.
So what do you read when you're ill?