Sometimes the very act of writing can trigger the creative process, even if you have nothing to say at the time and can’t think how to get going – it’s weird, but it works – Try writing a paragraph on something you’re comfortable with, whether it’s part of a scene, a well-known description or some fresh fun dialogue between two or more of your characters about something not important and not related to their story – The reason for it not being important or related is that it removes all stress from the exercise, you’re not trying to create something vital, you’re just trying to get the flow going.
Basically, this gets you physically moving on the task while waiting for your creativity to warm up and get into gear. At times, physical action is easier than mental action. It also gets your mind on the characters or location or story itself, and away from anything outside that realm.
If it works for you as it does for me, by the time you get halfway down the page, something happens. It’s like part of your brain wakes up and thinks, “Heck, I’m supposed to be writing,” and takes over. Words that are more descriptive pop into your mind or you find yourself editing sentences or coming up with better ideas. Point is, suddenly you have something more to say and what you are working on might shape into something else, or you can move onto where you want to be and begin to get some serious writing done.