Zig Ziglar has been a motivational speaker for almost 40 years. Years ago, Dr. Oz's mother-in-law gave him Zig's tape, and Dr. Oz instantly became a fan. "He talks about stuff in his life that's real—it's very authentic, and the stories are compelling," Dr. Oz says. He talks with Zig and his daughter Julie Ziglar-Norman about Zig's career and how business has changed over the years .

Before becoming a motivational speaker, Zig worked as a salesman, and he says he uses those selling tools to inspire others. "If you can encourage people, you are doing a service and it helps everybody," Zig says. He also stresses the importance of having a "home court advantage." "If things are good at home, I have a better chance of doing well out in the community," he says.

At 81 years old, Zig remains a dedicated student, reading three hours a day to add new material to his speeches. And the Internet has only helped spread Zig's messages. Julie says that the company now offers podcasts and free newsletters, and all Zig's material is available on his website. "You can't give enough away, and that's what we're trying to do, because what Dad has given this country and many others is a lot of hope and inspiration," Julie says.