Dr. Oz says he still remembers the first time he got a call from Oprah's producers.
"I wasn't really clear on this Oprah phenomenon," he says. "[I knew] everyone learned from it, and I remember grabbing a clean pair of scrubs. … I hopped on the plane, and I came to Chicago."
Oprah says Dr. Oz's impact on viewers' health has been huge. "He has taught us how our bodies work, how to get healthier, how to live longer," she says. "And he's made medical mumbo jumbo that [doctors] sometimes speak make sense to us."