Personally I see no reason for any beliefs - a belief is simply accepting something without any evidence.

I also see no reason to believe that the only things that exist are things science has studied. Obviously science keeps pushing farther and discovering more, it's an ongoing process. Plus it's likely there are some things immune to scientific investigation. I don't mean the superstitious things like ghosts or gods, at least in the stereotypical ways people usually mean those things. It's clear to see how primitive superstitious people dreamed those things up.

As for the actual question of the OP - my driving force is art.

It gives me a focus and a constant goal to work toward, which will always be there. No matter how good you get you can always improve. Many people, once they're out of school and have a steady job, just give up and accept that as their life, which leaves them feeling empty and like life lacks a meaning or a purpose. During those times when I'm not pursuing art (which are all too frequent) I know that feeling myself. But the drive to always push myself coupled with the immense feelings of accomplishment and triumph when I actually do create something worthwhile or reach a new level of ability give me a succession of peaks of positive emotion and positive reinforcement that I think many people lack after childhood.