I wanted to do a blog post about getting through writing slumps, because of something someone said on Twitter. (I can't remember what it was now, but that's how my brain rolls lately.)
A lot of people talk about the mid-book slump. Writing the beginning of a book is exciting, everything is new, you're creating the world, meeting the characters for the first time. The end is also exciting, because all the plot threads are tying up and you should be done soon.
The middle is the hard part, where you have to make the magic happen and start pulling things together, increasing the complication but starting to find answers to mysteries. You have to make all the cool stuff you came up with in the beginning make sense. You have to set up the end. The story engine has to be fully engaged, etc.
Sometimes it feels like a slog, and that's when you want to quit and go write something else. You want that really, really bad sometimes. If you do that with every book you write, it's going to be a problem and end up getting you zero finished books. (This, by the way, is why agents, and publishers who take unagented submissions, only want to see finished books from new authors. It's a lot easier to start a book than to finish it, and they want to make sure you can finish. A lot of people are certain they can, and then don't.)
So if your book-middle feels like a horrible slog and you'd rather go out and shovel snow or haul rocks or dig holes in the back yard, it isn't necessarily a problem. It's just that middles are hard.
But one thing I've noticed about myself is that if the writing doesn't come easily (and it's not just because I'm tired or unwell or stressed) then the chances are good that there's a problem that part of my brain is aware of even though the rest of me is willfully trying to ignore it. Figuring out what that problem is can be tricky, but first you have to figure out whether it's actually a problem.
I think you do need to ask yourself some questions. Is the book-middle like climbing a mountain backwards through a mud storm because you're tired and need to just keep going? Or is there an actual problem? Is it a pacing issue, are things moving too slowly? Are the characters still in character, are you making them act in ways you kind of know they wouldn't just to make your plot work? Is there something you're trying to do now that needs more setup earlier in the book? Did you forget to put in something you know you really needed?
Or are you actually getting bored with your plot? Because if you're bored with your plot, readers may be bored with it too.
If you're saying: "I have to write this part and I don't want to." Ask yourself: Do you really have to? Is it necessary for the plot, characterization, the story? Why don't you want to? Is it not right for the pacing, slowing things down when it should be speeding things up? Maybe it doesn't need to be there.
If you don't like it anymore, it's okay to make something else happen instead.
You can always take a step back and re-imagine your plot. You should know the characters better at this point; maybe your plot needs to change to accommodate that. (It's often hard for some writers to create a character in a vacuum. It's only when I write characters interacting with other characters and facing situations that I start to get a real sense of who they are and how they behave under stress.)
What is the coolest, most exciting thing that could happen here that will still fit the story you want to tell? Maybe you should be writing that instead.
Your plot is not carved in stone, even if you did an outline. One thing I've found out over and over again is that plot points can sound great in the outline and it's only when you start actually writing those scenes that you see the flaws.
This is where experience and understanding how your own writing brain works is important. The only way to get experience is of course to keep writing through those middles, no matter what you have to do to get to the end.