John F. Kennedy. JFK transferred from Princeton to Harvard in 1936, where he played a decent game of football but was described as too skinny to be a game-changer. His backstroke, however, earned him a place on one of the best freshman teams in Harvard's history. He then went on to do other important stuff...like becoming the President of the United States. NBD.

John Feinstein. In ninth grade, Feinstein faced the truth: he'd never be a star basketball player. Recruited by his high school's swim coach, he continued his swimming career at Duke, despite describing himself as burned out. Today, Feinstein is a multimedia sports journalist who provides commentary for TV, hosts radio shows, and writes award-winning books. Check out his book, A Season on the Brink. FYI, it's about basketball, not swimming.

Diana Nyad attempted the swim five times before her successful go in 2013. See what we mean about swimmers needing endurance?

Diana Nyad. The great-great granddaughter of the woman who created Mrs. Winslow's Soothing Syrup (i.e. morphine for babies), Nyad swam for the Foresters at Lake Forest College in Illinois, where she focused on distance events. This led to her love for marathon swimming, which resulted in her becoming the first person to swim from Cuba to Florida without a shark cage. Eep. No, thank you.