Why is Serena Williams such a good player?

She is like most sports superstars or any experienced person, many grew up playing the game and over the years have mastered it like Serena and her sister have but chances are they ate, slept, dreamt, talked, bathed tennis so much it became natural to them.  So Ancient Hippy is correct in practice and more practice til one is sick of it and then find a way to practice more will make you a star or superstar in something you love doing.  Good luck