When I was in school, I had a really bad habit of getting bored. If I wasn't challenged or things became stale, I stopped caring about the class. Obviously, I didn't do so well in high school and it wasn't until I reached college, where I could explore different things, that my grades started to get better.
The habit hasn't died, I still get "bored" easily. Instead nowadays, when I feel myself getting bored, I try to figure out why I'm bored. I look at what I'm doing and figure out if it's become stale or is there more? Maybe I've only been scratching the surface, and it's time to look deeper or out. Focus is good, but extreme focus means you miss out on a lot.