Henry Winkler, best known for bringing “The Fonz” to life on Happy Days, is sharing how he spent years battling an invisible challenge while at the height of his Hollywood career.

The beloved actor played his iconic role for 11 seasons, all while struggling with dyslexia—something he didn’t even know he had until adulthood. Winkler said he was finally diagnosed at 31, only after his stepson was tested in third grade.

“My stepson, who’s now 53, was diagnosed, and everything the doctors described about him sounded exactly like me,” Winkler revealed in an interview. “It was the moment I realized I wasn’t stupid. My brain was just wired differently.”

Growing up, Winkler said school was a painful experience. Teachers scolded him, classmates mocked him, and he was often punished for not performing well academically. The emotional scars lingered long after he became a television star.