Reading two books at once

I've started doing something I've never done before - read two books at once. I find two fiction books at the same time too confusing to follow, but it seems to work well for a non-fiction book and a novel. This only works with a how-to or recipe book, something like that, not a biography. I'm not always in the mood for non-fiction or sometimes don't have the focus, so then it's the novel. I have a need to read!