We've all heard the phrase "nice guys finish last," the basis being that "nice guys" lack the confidence and aggression needed to succeed in life, thus being trampled by their "mean" cohorts. Fortunately for all the inherently considerate folk out there, this is a myth.
It's entirely possible to be nice and successful at the same time. There are, however, some finer details to keep in mind. So put a smile on your face, get those mean insults out of your head, and start down your path to success.