Sanders says that you MUST love what you are doing if you are going to be the best at it. I respectfully disagree with her. I think you have to be gifted and have a professional approach.
Actor Marlon Brando didn't love his job and he would only perform if you paid him an outrageous rate yet he redefined acting. He also made some really bad movies into watchable ones.
Boxer George Foreman didn't like to hurt people and in a comeback fight at Caesar's Palace against Gerry Cooney, Foreman begged the referee to stop the fight because Cooney was taking to much abuse from his powerful punches. (His request was less than 2-minutes into the second round) - Note, Foreman won that fight with a brutal knockout punch and eventually reclaimed the heavyweight championship title in 1994 at 45-years-old despite his adversity to violence.
People are great for whatever reason but love is only just one component. There is a "B-Final graveyard" out there filled with swimmers who trained harder than anybody, loved the sport more than anybody, yet did not become the best. There is also a "champions' graveyard" with guys like Mark Spitz who never worked as hard as many of the "B-finalists" but found himself as a great athlete via an act of God or otherwise.
"...That's amazing! Michael Phelps is not just amazing for winning eight gold medals in one Olympic Games, but for having the desire and passion to go for his fourth Olympic team.
What drives each athlete is different. Some long for more medals, others long for faster times, but the bottom line is when it comes to the Olympics, money can't drive you. A paycheck doesn't get you the gold medal. It still comes down to fire, passion and love for the sport.