A while ago, I talked about Limitation in Poetry, and how forcing myself to follow very specific guidelines (ironically) ended up helping me think outside the box in terms of rhythm, word usage, imagery, etc.
Now, apply that to your own current WIP, be it poetry or prose. For instance, you can write entirely in iambic pentameter; you can write, as some others have, without using the letter ‘e,’ or without using adjectives or pronouns, etc. Find some way to force yourself to think about your writing in a different way, and see where your words take you from there.