When I am in the midst of writing a long work, sometimes I get dreary and weary. I find that it is hard to get to “the end”. I need some fuel. Something to gas up my writing.
That is why I write short stories.
They keep that “new” feeling in my writing. Most writers I know love to start a new work. It’s exciting. The feeling you get when beginning something new is like an addiction.
That is why I write short stories. To get that uplifting feeling of doing something different. And truthfully, there are more places available looking for good solid short stories (for pay!) than you can shake a stick at.
Also, taking time away from a novel can only help it. We need to be able to step back and analyze it with fresh eyes.
So, if you are having the middle-of-a-book blues, sit down and write something short. Find a market for it. You will be happy, be paid, and be able to go back to that book and see it anew.