i know this will sound cheesy but...

- force yourself to dream about what you're writing.

- what I also find helpful when I'm stuck writing or when I'm thinking of other better ideas (though I usually go ahead and start writing it and come back later), I think about and possibly write out character backstories. I think of something intriguing that maybe the reader will never know, but that I'll know. I'll know where the scar on his left knee came from. I'll know how she got her fear of butterflies. I'll know why his mother never talks about his father anymore.

- Plan out little scenes you want to happen in your writing and connect the dots. Choose the scenes that will make you want to start writing the moment you have a pen and paper (or a keyboard).

- Listen to music that sets the mood of your piece. Sometimes what I'm writing may not be the most inspirational or wow-factor piece but when I listen to music (right now I'm listening to Clair de lune) I feel the sudden urge to write.

hope this helps :)