To the world, he’s Dr. Mehmet Oz, but to his three grandkids he’s “Runka,” a name made up by his daughter Daphne Oz‘s oldest child, Philomena. “Everyone had a name but me,” he recently revealed to Closer Weekly in the magazine’s latest issue, on newsstands now. “One day, she called me Runka and I took it!”

Being a Runka to Philo, 4, Jovan, 3, and Domenica, 13 months, is the television personality’s proudest preoccupation these days. “The beautiful thing about being a grandfather is that you see the joy that you had as a father in your child. So there’s a multiplier effect,” Dr. Oz, 58, said. “Plus, you have the joy of the grandchild, and the best part — you can give them back!”

As a busy young surgeon, Dr. Oz missed a lot of important moments in the early lives of his own four children. “I spent a lot of time wishing I had done things differently,” he shared. “Now I get a redo.”

When he’s reading to his grandchildren, playing ball with them or making up games of pretend, Dr. Oz always looks for teaching opportunities. “Try to think about the values they need to have and how you’re going to play with them to reinforce those,” he explained. “[It’s things like] how to deal with failure and how to deal with success.”

Grandchildren, he believes, shouldn’t be spoiled or handed victories they don’t earn. “I love doing competitions — like a pirate hunt,” Dr. Oz, who recently spoke at the Beacon Awards in NYC, admitted. “I want them to deal with failure.” If he can teach his grandkids to fall, get up and try again, he’d feel like he’s done his job. “I want them to realize that it’s the joy of overcoming an obstacle that makes life worth living,” he said. “If they get that one lesson from me, I’m good!”

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