It is not IQ, as some would believe (or "innate ability" or "natural gifts," although both of those things are certainly helpful!).
According the "The success myth," research shows that much of what makes certain people successful where others are not boils down to small things like persistence, having a plan and coping with adversity.
This is good news: you don't have to be a genius or be naturally adept at something to be successful; hard work, perseverance and focusing on what is important is just as valuable and more helpful in the long run.
So get out there and do something fabulous!