Shonda Rhimes Opens Up About Overcoming Shyness, Weight Loss and Her Journey to 'Year of Yes'

— -- Shonda Rhimes is a powerhouse in Hollywood as the creator of “Grey’s Anatomy” and “Scandal” and the executive producer of “How to Get Away with Murder,” but she says she was hiding a painful secret.

With three hit ABC shows, her workaholic tendencies and her panic attack-inducing shyness left her secretly miserable.

In an interview with "Nightline," Rhimes said her fear often led her to turn down interviews and glamorous invitations. But that all changed over Thanksgiving two years ago when she said her oldest sister pointed out to her that she would “never say yes to anything.”

Those words stuck with Rhimes. It launched her on a journey to make 2014 her year of saying "yes" to the things that scared her instead of running from them.

She's now opening up about the biggest changes in her life, from losing more than 100 pounds to overcoming a fear of public speaking to going for new opportunities, which she details in her new book, “Year of Yes,” out on Nov. 10.

“In writing the book, the honesty that came out of that was so comfortable,” Rhimes told “Nightline.” “It was part of not needing to hide. I was not afraid of anything. I no longer cared what anybody thought about me.”

Watch the full interview on "Nightline" tonight at 12:35 a.m. ET

Rhimes writes about the first thing she said yes to was going on “Jimmy Kimmel Live” in April 2014 for an hour-long special to promote the season finale of her political TV drama, “Scandal.”

Next was giving her now-famous Dartmouth commencement address in which she told graduates “A hashtag is not a movement” and to make change means taking action, “be a do-er, not a dreamer.”

She told "Nightline" she got to a point where she realized she was working hard in all aspects of her life except being healthy. In her book, Rhimes writes about the moment of utter humiliation that made her say "yes" to losing weight.

“I got on an airplane to go to New York, and First Class seat, you know, they’re bigger, they’re more comfy,” Rhimes told “Nightline.” “And I tried to buckle the airplane seat belt, and it would not buckle, and I remember feeling horrified and thinking, ‘What am I going to do?’”

For a long time, Rhimes said, she thought wanting to be “thin” felt almost anti-feminist, even “shallow and misogynistic.”

“I had a real problem with it. As a feminist, I felt like, ‘Why am I even having this conversation with myself?’ And I would fight for any other woman’s right to be whatever size she wanted to be,” she told “Nightline.” “It was amazing to me that I had such ambivalence about it.”

But when she decided to make a change, Rhimes said she spent more than a year working on being healthy and changing her diet, joking that she even learning to love salads.

“It still sucks,” she said. “I’m always going to want to eat fried chicken.”

Today, she said she has “a lot more” energy, which has changed her life in many ways.

“I put my 3-year-old on my back and we galloped up and down the hall for, like, 20 minutes. And then I put her down for her nap,” Rhimes said. “I sat down and burst into tears because I really sort of realized that, like, I don't know, a year ago that -- I might literally have died. That would've given me a heart attack.”

Although she is notoriously private, Rhimes’ fans know her through the little pieces of herself that she inserts into the strong female lead characters she creates on her shows.