That's why it's so important to find a way to turn off your brain for a few days. You have to rest the creative part of your brain - the storytelling center of it all - so that you can return to your story revitalized and ready for the curveballs ahead. It's like a muscle: you exercise it, you rest it, and it gets stronger.
I just returned from a trip to California, where I let the little child inside me run free at Disneyland. It was a great vacation for my brain, not to mention a fun trip for the rest of me (although my stomach didn't appreciate all the roller coasters). I got to enjoy the fruits of someone else's creativity, and that inspiration will carry over into my writing. The storyteller in my head is ready to get back to work.
If you can't go to another state, then try to work in some time for a mini-vacation. Sometimes, I like to design board games or lose myself in a good book. I sit down with raspberries and rootbeer, and I watch an old black-and-white movie. I force myself to think about something other than a story.
So if the storyteller in you is feeling worn out, or if you're facing writer's block, try a mini-vacation. Force yourself to think about anything but writing. Let your creativity take a break.
And then return to your writing project renewed.