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.

“There was a time when red wine and popcorn was just a meal for me,” she joked, referring to the “Scandal” leading lady Olivia Pope’s signature snack.

But the character Rhimes most closely associates with is Dr. Cristina Yang, the ruthlessly competitive, head-strong heart surgeon on “Grey’s Anatomy,” who chooses to walk away from marriage to dedicate herself to her life’s work in the end.

“I don't even think I realized how intense that relationship was until we were in Season 10 and she was getting ready to leave, and I suddenly realized that I was grieving this person that was going to depart,” Rhimes said. “But the two of us had so many similarities. We were very intense about our work. We both have sort of the same sense of humor. Our sense of loyalty is very similar, and our sense of -- our work ethic and our feelings about relationships are very similar. So there was a lot about us that felt very much the same.”

One key difference though is that Cristina Yang is very clear on the show that she never wanted to have children, and even has an abortion in one episode -– which sparked enormous discussion at the time. Rhimes is not married, and said she doesn’t want to be married, but she has three children.

“I would have 47 kids if I thought I could get away with it. I love children,” she said. “But I did try it out on her [Cristina Yang], because I thought it was really important to see that kind of woman portrayed in that story, because you never see that.”

“And that also feels to be like another taboo,” Rhimes continued. “A woman who doesn't want to have kids is sort of a mystery to people. That's a question they're asked the minute they get married, it's a question they're asked constantly, ‘Don't you want to have kids?’ And I feel like that's completely unfair.”

Rhimes doesn’t shy away from pushing the limits of social norms on her shows, and has no problem throwing out the “fairy tale ending.” “Grey’s” fans were shocked when the beloved character Dr. Derek Shepherd, played by Patrick Dempsey, was killed off in Season 11, leaving Dr. Meredith Grey, the lead female character, to put herself back together again.

But in real life, Rhimes said it’s about women making their own path.

“I don't know that I think women have to throw out the fairy tale ending,” she said. “I just think they have to decide what their fairy tale ending is-- and not go with the standard one that everyone's told them they're supposed to have.”