There are a lot of factors that go into greatness, many of which are not obvious. A variety of Olympic and professional athletes tell us how they made it and what they sacrificed to get there. And if you can identify the sport most likely to get a kid into a top college — well then, touché! (Ep. 3 of “The Hidden Side of Sports” series.)

The San Francisco 49ers, one of the most valuable sports franchises in the world, also used to be one of the best. But they’ve been losing lately — a lot — and one of their players launched a controversy by taking a knee during the national anthem. So why is everyone there so optimistic? To find out, we speak with the team’s owner, head coach, general manager, and star players, including their new $137.5 million quarterback. (Ep. 2 of “The Hidden Side of Sports” series.)