A teacher once challenged me this prompt. It's interesting, and you learn a lot about art and yourself this way. This prompt is an art prompt OR a writing prompt, really.

~Determine what your worst fear that could possibly happen is.

And then go out of your way to prove that it is real. Write "non-fiction" accoutns of sightings, etc.

It's really crazy the stuff you come up with.

If you dislike the negativity, I suppose you can do this with something you REALLY WANT instead of your worst fear..