Pushing the Limits: Swimmer Katie Ledecky makes history

“CBS This Morning” is kicking off a new series, "Pushing the Limits," where we profile seemingly ordinary people doing remarkable things. Katie Ledecky is called "the best swimmer on the planet." She started building her legacy at age 15, winning her first gold medal at the London Olympics. She's broken 10 world records, one of them, almost by accident. Norah O’Donnell spoke to Ledecky on how she sets -- and beats -- her personal bests.