Maybe the right question to ask is: Why do some people decide to practice a lot in the first place? Could it be because their first efforts proved mostly successful? (That’s a useful reminder to avoid romanticizing the benefits of failure.) Or, again, do they keep at it because they get a kick out of what they’re doing? If that’s true, then practice, at least to some extent, may be just a marker for motivation. Of course, natural ability probably plays a role in fostering both interest and success, and those two variables also affect each other.