Music is a huge motivator indeed.
Since I don't ride with headphones on, I try to listen to my favorite music quite loud before each time I head out for an intense ride. Inevitably one of the melodies gets stuck in my head, and I'm 'listening' to it for most of the ride. Of course, it becomes 'loudest' during the more epic portions of the ride - climbs, sprints, or long stints of peak output.