Sports: Road Cycling
Highlights: 2-time Olympic gold medalist (2008, 2012) in the individual time trial; 2-time (2006, 2009) time trial world champion; 3-time (2005, 2006, 2007) national time trial champion; 2-time (2004, 2006) national road race champion
Quote: "I am a mom first and a cyclist second—that is how it will always be."
Fact: Armstrong retired from racing in 2009 to start a family, but returned for the 2012 Olympic Games to defend her crown.
AT50 Point Total: 37.5
Kristin Armstrong has always been an athlete. First, as a teenaged junior Olympian swimmer, and next as a serious triathlete who competed in the 1999 Ironman World Championships. So when she was diagnosed with osteoarthritis in 2001—a condition that would prevent her from running again—it, surprisingly, turned out to be a bittersweet moment. She had to quit being a triathlete in her prime, sure, but she also discovered that cycling was her true calling. Within two years, she was racing professionally and, in 2004, she won the U.S. road racing championship (her first of two) and competed in the Olympics. She'd go on to master the individual time trial, winning three national championships, two world championships and Olympic gold medals in 2008 and—following a one-year break to have a baby—2012. Today, Armstrong is the most decorated female cyclist in U.S. history.