"I remember some people telling me my nose was too big or my eyes were too small, that I could never be on a magazine cover," Bundchen told People in a recent interview.
Bundchen, 35, first began modeling at age 14 in her native Brazil.
"It wasn't easy to be 14 and hear that kind of criticism. It made me feel insecure," she said.
"I already felt weird because I was taller and looked more mature then most girls my age," she continued. "I just knew that I wanted to do my best and see if I could make it."
So Bundchen turned to her family for advice.
"I told my dad, and he said, 'Next time, tell them, I have a big nose and that comes with a big personality,'" she explained. "At that point, I felt, if I kept working hard and giving my best, it would all work out."
Turns out she was right. Bundchen, who moved to New York City at 16, has now spent over two decades in the fashion industry.
"It's still hard to believe that it's been that long. Time does fly," she said.