Many writers think they have several books "in them." Usually they are written in sequence, and trouble with one book can delay starting the next one.
As an alternative, consider working on two or more books at the same time. Lots of people read several books during the same week, changing books whenever they feel like it. There's no reason not to switch the books you're writing, too.
This way, if you you hit a writer's block and stall on one book, or simply get out of the mood, you can switch books and keep being productive.
This doesn't work all the time, but if the books are very different the change can be both relaxing and stimulating. I once simultaneously wrote a humor book and a technical book. I'm now working on several books about publishing plus a true-crime book.
Also, you may find that a concept or some actual words in Book A can be used in Book B. Or maybe even give you an idea to write Book C.
What was going to be my Book C became my Book B, but parts of B are in C, and A gave me the ideas for D and E.
And, even if you're working on just one book, you can skip around within the book. If you're having trouble with Chapter 3, work on a chapter that happens later, or go back and edit chapter 1.