In short: you are going to have to find a muse.

For me this could end up being a number of things— a song, a television series, an anime, a video game, a novel, a poem, a piece of art. If I want to get into a fantasy mood I look for something relative to that in any of the above categories. Writers are artists and are nothing when uninspired, we need the motivation and heart of what drives us or else we make our art end up as exercises in clinical futility.