If game development is in you, you'll continue to learn new things, study game dev, read books on game programming, graphics, AI, and/or whatever else. My oppinion is, you can't really force yourself to program games - well maybe if you do, it won't last long enough.
What motivates me? The fact that I love game programming and 3D graphics modelling, and one day, I want to become a professional game developer; it's my dream. So, look out for my name as the newest member of EA Games' developers team! Hehe, just kidding.