There are a lot of factors that go into greatness, many of which are not obvious. As the Olympics come to a close, we revisit a 2018 episode in which top athletes from a variety of sports tell us how they made it, and what they sacrificed. SOURCES:Lance Armstrong, former professional cyclist.David Canton, director of African American studies and professor of history at the University of Florida.David Epstein, science journalist and author.Domonique Foxworth, former professional football player.Justin Humphries, former professional baseball player.Andre Ingram, professional basketball player.Shawn Johnson, former professional gymnast and Olympian.Steve Levitt, professor of economics at the University of Chicago.Simone Manuel, professional swimmer and Olympian.Brandon McCarthy, former professional baseball player.Mike McGlinchey, offensive tackle for the Denver Broncos.Daryl Morey, president of basketball operations of the Philadelphia 76ers.Lauren Murphy, professional mixed martial artist.Kim Ng, advisor with Athletes Unlimited Pro Softball, former general manager of the Miami Marlins.JJ Redick, head coach for the Los Angeles Lakers.Mikaela Shiffrin, professional alpine ski racer and Olympian.Mark Teixeira, former professional baseball player.Sudhir Venkatesh, professor of sociology at Columbia University.Kerri Walsh-Jennings, professional beach volleyball player and Olympian. RESOURCES:"Compromising Talent: Issues in Identifying and Selecting Talent in Sport," by Joseph Baker, Jörg Schorer, and Nick Wattie (Quest, 2017)."Practice and Play in the Development of German Top-Level Professional Football Players," by Manuel Hornig, Friedhelm Aust, and Arne Güllich (European Journal of Sport Science, 2016).The Sports Gene, by David Epstein (2013)."The Effect of Deliberate Play on Tactical Performance in Basketball," by Pablo Greco, Daniel Memmert, and Juan Carlos Pérez Morales (Perceptual and Motor Skills, 2010). EXTRAS:"The Hidden Side of Sports," series by Freakonomics Radio (2018).“How to Become Great at Just About Anything” Freakonomics Radio (2016).