c = l * t + g¶

Found a link to a good formula on Robert-Reinder Nederhoed's weblog for thinking about your career development

career = learning_effort * time + natural_gifts

You can't do anything about your natural gifts and your time is the same as everyone else's. What makes the difference is the how much you learn.

According to the article, the best way to learn constantly and consistently is to explicitly learn from your mistakes.