Henry Winkler Pushes Back on His 'Nice Guy' Image and Says 'Gratitude' Brings Him Joy (Exclusive)

The star opened up about his reputation to PEOPLE ahead of the release of his memoir 'Being Henry'

Henry Winkler has some thoughts about his "nice guy" image.

"What I finally realized is I’m not nice," the actor, whose book Being Henry: The Fonz…and Beyond releases on Oct. 31, tells PEOPLE in this week's issue, addressing his reputation as one of the most likable stars in Hollywood.

A description of himself he would accept is "joyful." A decade of therapy and self-reflection have taught Winkler, 77, that his sunny, kind nature comes from a place of deep gratitude.

"I'm enjoying being on this earth. I'm grateful, and my gratitude makes me joyful," he says. "And that is the truth. I get up that way."

Related: Henry Winkler on Career Longevity at 77: 'I Will Stop When I Have to Stop'

But even Winkler has his moments when he feels a spark of irritation, especially after a disappointing encounter with someone. "I'll tell you what really makes me angry is not being seen, being dismissed," he says. "It is still an old trigger, and it is palpable. It is powerful."

The Happy Days alum, who recounts his difficult childhood growing up in New York with his German refugee parents in his memoir, says being rudely brushed off when approaching his famous peers to say hello or share a compliment can leave him reeling. "A curtain comes down [in my mind]. Boom," he says of those off-putting moments. "I mean, it is hurtful, unnecessary. Because all I want to do is tell you how much I appreciate what you do."

However, these experiences are not why he's so focused on putting positive energy out into the world. "I'm kind because I appreciate it. I'm kind because I understand what it is not to have received kindness," he says.

Considering his good-guy persona, Winkler relished showing off different chops in his Emmy-winning role in the HBO comedy series Barry, which aired its fourth and final season earlier this year. He played Gene Cousineau, a washed-up acting coach with serious anger management issues, allowing him to dig into a darker, grittier side of himself.

He recalls doing an early table read with his Barry costars and shocking an HBO executive with the intensity of his performance. "I'm talking to Sarah Goldberg … and (in character) I'm telling her that she is the worst actress. 'You make me vomit!' And I hit the table. I say, 'You are full of bulls--t!' And the man jumped, and later told [show creator] Alec [Berg] and Bill [Hader], 'I had no idea that was in Henry,'" Winkler recounted.

"That kernel of 'I did not know' flowered like a rose garden over the four years of doing that show," he added.

For more on Henry Winkler, pick up the latest issue of PEOPLE, on newsstands Friday.

Winkler says Barry came along at just the right time in his career — and his personal evolution. He admitted that he would not have been ready for the role of Cousineau before working regularly with his therapist, whom he credits for helping him to dig deeper within himself and become more attuned to his emotions.

"I could not have made that character as full as Gene is," he explains. "I was not in touch."

Winkler says therapy has not only bettered his career but also his relationship with wife Stacey Weitzman, to whom he has been married for 45 years.

"That's why I say if I were to give a gift to my therapist, I would have to give her something as big as a skyscraper," he says. "Because [my] book is about me being who I thought I should be and inching to being something I talked about but couldn't live, which was being authentic."

Related: Henry Winkler Reveals He Rode Fonzie's Iconic Motorcycle Only Once — and Crashed It

Looking back on his four decades in showbiz, Winkler says he realized he spent too many years holding himself back due to crippling self-doubt caused by his dyslexia, and now extols the importance of taking risks.

"You have to jump off the precipice and just trust you're going to fly," he says, remembering some lean years when the acting jobs weren't coming and he had a family to support and a mortgage to pay. That vulnerable place ultimately led him to tap into new opportunities in his career.

Related: Henry Winkler Struggled with Lines as the Fonz, Felt 'So F---ing' Angry After Dyslexia Diagnosis (Exclusive)

"What am I going to do?" he recalls wondering at the time. "And then somebody suggested I become a producer. I start off saying, 'I can't do it. I'm dyslexic. I have no idea what the business is. I can't do it.' And then finally you say, 'Oh, just shut up and try.'"

"So, I think shut up and try is the [lesson]," he continues. "It sounds simple, but it might be the most important lesson that I could pass on to somebody."

Henry Winkler's memoir Being Henry: The Fonz .... and Beyond is available Oct. 31 wherever books are sold.

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