It's really not that difficult to read more than one book at a time. And don't worry that you will get confused by the storylines or mix up characters. Unless you are reading two similar books, that doesn't happen as easily as you may think.
Here are some tricks that I use when reading more than one book at a time:
1. Have a primary book.
This is usually the book that I am reading for my Wednesday night book club. We very frequently read one book per week, so this is the book that I must concentrate on if I am to get it read. I read this during breaks in my day and in the evening instead of watching television (unless one of my "must see" shows is on, of course).
2. A book while walking.
You would not believe how people make fun of me because I read while I walk! I walk in my neighborhood, know the streets well, and always face on-coming traffic, which is sparse. It is not dangerous under those conditions. And it helps to pass the time while I am getting a health benefit. I always choose a paperback for this, since they are lighter to carry. I walk about an hour, so I can cover quite a few pages in this precious, uninterrupted time.
3. Choose a secondary book on a mobile device.
If my primary book is fiction, I will choose a non-fiction here. Some non-fiction that I have read lately include "The Immortal Life of Henrietta Lacks", "Killing Kennedy", "Killing Lincoln", and "The Witness Wore Red". Likewise, if your primary is non-fiction, choose a fiction book. It is very easy to keep subject matter and characters separate when the genre is so different. I read these when I am waiting in line, at the doctor's office, or any other time I am away from home with down time. That's why it's important that this book is located on your mobile device.
4. Audio book.
I have to admit that I am not a good audio book "reader". My mind wanders and my heart is just not into it. Usually, I am multitasking while a book plays in the background, so that is not a good thing when retention is needed. This is great media, however, for a memoir or a book of comedy, like Tina Fey's "Bossypants".
See? That's four books at a time!
And if you feel up to it, add this:
5. Before bed.
This is a wind down time when you need just a few pages or so to help you transition from sofa to bed. For this, I suggest short stories, like Flannery O'Conner's "A Good Man is Hard to Find" or Shirley Jackson's "The Magic of Shirley Jackson". Read a story or essay a night, and you will be finished before you know it!
You are up to 5 books now!
Get to reading, reader!!