I saw a very interesting blog at 37 Signals on the quote “the things you do more often are the things you get good at.” It’s aimed more at a business model, talking about the idea of building a service for free without having an idea of how to later convert that to profit.
However I think there is something else here. For most of us, outside of running our own business, the things we do most often are the things that we are interested in, or that speak to us. They are the things we like, and if we are self-aware, we recognize these things and look to build them into our life.
Life is short, and your career is a big part of that. I recommend that you understand what you like to do, and then find a way to do more of it in your career. And enjoy your job more.