Words are hard. You know, writing things down on a blank page, putting one after another in some semblance of order. It's hard. There are books and books and books that tell you how to do so, how to pluck words out of the air and create an idea.
I think I might start picking them out of a dictionary.
Jim Butcher, one of my favorite authors, came up with his second series of books on a dare. He said good authors could take a bad idea and make it good, so he challenged someone to give him two random ideas and he would right a good story. He was given Roman soldiers and Pokemon. Out of those, he created the Codex Alera. In my opinion, they are great books.
I think it's a great exercise to take random words, random themes, and put them together as a writing exercise. It gets the brain matter working and the thoughts flowing together.
So here's what you can do. You can either cut out words, pictures, or themes from a magazine, internet printouts, books, etc, and keep them in an envelope to pull out when you need to. Or, if you don't like to plan and/or loose your envelope (do you get the feeling that's happened to me?), grab a book off the shelf, flip through the pages, and stick your finger on a few words. There you go.
Now go write already.