Musician. Most of time, it's just practicing for something that lasts only a fraction of the practice time spent. Composing is also not just fiddling around with your instrument, spontaneously becoming inspired, and then knowing exactly what to do with that inspiration. It's way more frustrating than that. You'll just have days when no ideas come to mind, or every idea sounds terrible in your mind. And many times you'll work with an idea and have something that works on its own, but not well enough in the overall piece. Back to the drawing board.