Let's face it, there will be times when you'll have to work without motivation and inspiration. It's in those situations where efficiency and giving yourself rewards and treating yourself well are extra important.
Basketball star Kobe Bryant says (about basketball) that he "honors the craft". That's why he's so good at the game.
That's what you need to do. Take what your already good at and get better. Honor the craft. Don't wait for inspiration, go after it.