Have a teachable spirit and the willingness to listen to an editor or an established author. If you think not one jot or tittle of your work should be touched, you will fall short in your efforts to improve your writing and to be published.
If you are not yet published, listen to constructive critiques. A constructive critique will give you guidance on how to make your story better in content, narrative, dialogue, etc. Don't shoot me, but if all you get in a critique is don't use 'was', 'ing', or 'ly' ever, or 'you broke a rule', you are being critiqued by inexperienced writers.
To keep the passion alive for writing, try variety. Listen to inspiring music. I prefer classical and movie soundtracks. Take your laptop outside on a warm day, or move to a different area in the house. If you don't have a laptop, write by hand in a notebook away from your computer. Don't answer the phone, unless the caller id screen tells you it may be important.
When you have those moments where the words are not flowing, be patient. As a writer friend told me when I shared with her what was happening, 'continue to stare....something BIG is about to break!' But do not neglect your muse. Dwell on the scene. Listen to inspiring music and read or watch a movie in your genre.
Next time you sit down and open a novel think of the work that the author put into writing it. It took months to write, perhaps a year. They went through moments where they froze, moments of intense creativity, moments of despair wonder if it was good enough, and lonely moments too. Writing is hard work. But we do it because we love it and we love our readers and want to please them.