Barbara Corcoran's Favorite Mistake: Believing She Was Stupid The best mistake I ever made was believing that I was stupid. It was a childhood thing, but it played out big-time as an adult. It scorned me the rest of my life - in a good way. I hadn't learned to read by third grade, which wasn't unusual for some kids. I knew something was wrong because I couldn't see or understand the words the way the other kids did. I wasn't the least bit bothered - until I was sent back to the second-grade classroom for reading help after school. I was petrified when I walked in because Sister Stella Marie was standing there waiting for me. Sister Stella Marie, you have to appreciate from a little kid's perspective, was the nun from hell. Every kid in the school was terrified of her, and I was no exception. Ten minutes into the lesson, I was sitting there thinking about how I was going to catch more guppies, these tiny little fish in the Hudson River, if I tied a long string to the neck of a milk bottle and pulled it up really slowly to scoop up the fish. I was thinking about that very strongly, when Sister, as we called them all, pulled me right up out of my chair. She was inches from my face, and she said, "If you don't learn to pay attention, you will always be stupid." I can still feel the heat of that. She labeled what was wrong with me, right then and there. She was a tough nun, and at 8 years old, I believed her, and became the quietest kid in school. But my greatest strength as a child, I realize now, was my imagination. While every other kid was reading and writing, I had seven whole hours a day to practice my imagination. When do you get that space in your life, ever? I know that it is what built my real-estate business, because I had an innate ability to picture everything in living color, as though it had already happened. Michael Lewis / Corbis Outline My insecurity also made me a meticulous preparer. I worked twice as hard as everyone else because I was constantly trying to prove that I wasn't stupid. Even to this day, I can succeed at something, but I'll be in another new situation and panicked that I'll have a public failure. But, boy, does that make me work hard to make sure I don't. That moment was so impactful and played out in a million ways in my life. I think that's a mistake that a lot of people make with kids. They narrowly define kids by their school grades. That view has improved, but I still think people try to make their kids like every other kid. Most great entrepreneurs I know are nothing like the other kids. They're almost like tangent lines - those lines that seem to go nowhere. Nothing connects them, until they get out in the real world. Then they connect just fine. Barbara Corcoran is the founder of the real-estate company the Corcoran Group, a contributor to the Today show, and an investor on the ABC series Shark Tank, premiering Jan. 20.