You're right, I didn't choose my words well. I should have dropped "career" from the statement and just left "pursuit," something you do in a large part for its own sake. And maybe I should say "It's not brilliance that defines a good X," because clearly you can be a subpar artist/programmer/teacher/etc. and get by on some combination of luck, connections, politics, organizational apathy, and so on, but if you really want to be the best damn X you can be, it's going to involve a lot of elbow grease no matter what that X is.