if you want to write, get your writer's head on. If you want to take pictures get your photographers head on. Effort spent in being able to quickly and efficiently get the 'right head on' for the task is effort well spent. When you have the right head on you see endless possibilities in that area...feeling barren is a sure sign you are approaching something with the wrong head on. One way to get the right head on is to leap in head first with no thought of quality, only reacting to every creative impulse however weak, never saying 'no' to any idea. This naturally becomes refined once you get the right head on. Taking a break when you'd normally work is another way, so is travel; but these methods have thier own dangers in terms of providing opportunities to bunk off and consume rather than produce. The key, I suppose, is in planned use of breaks and travel.