Sheryl Sandberg, chief operating officer of Facebook Inc., said she hesitated to give the TED talk in December 2010 that has catapulted her as a major voice for women and served as the launching pad for her new book, "Lean In."
Sandberg told ABC News' Elizabeth Vargas that she had never talked publically about being a woman.
"Everyone told me not to. They said, 'If you give a public talk on women, people are going to notice you're a woman.' I was like, 'Okay, well.' But I did it," she said.
Sandberg said she worried that others might think she was asking "for special treatment or about to sue them."
"But over the last 10 years in the work force I was so alarmed as more men were leaning in and progressing. And women were working the same hours, working just as hard. But not getting the promotion, not getting paid as much," Sandberg said.
Over 2 million views on YouTube later, a new book and a nonprofit LeanIn.org, Sandberg said she has received emails and letters from inspired women from all walks of life who "sat at the table."
On LeanIn.org, women are encouraged to tell their stories about speaking out, gaining more confidence and helping each other achieve their goals.
One of the stories is from a mother who gathered the courage to speak to her son's principal to ask for another teacher for her child. Another story is of a woman who faced her rapist to testify against him.
Of course, Sandberg shares her own experiences of splitting chores and childrearing with her husband, while her career skyrocketed from chief of staff for the United States Treasury Department under President Bill Clinton to Google's vice president of Global Online Sales and Operations. Sandberg is also a director of The Walt Disney Company, which owns ABC News.
Watch Sandberg's interview on "Nightline" tonight and more on "Good Morning America" Tuesday
Sandberg admits in her book that before she became the COO of Facebook in March 2008, she almost readily accepted Mark Zuckerberg's first salary offer.
"When Mark offered me the job at Facebook, I had been interviewing with him for six weeks. I was dying to get this job. And when he made the first offer, I thought it was fair. And I was about to take it gratefully," Sandberg told Vargas. But Sandberg's brother-in-law told advised her, "No one takes the first offer."
"And I said, 'Well, if I negotiate, maybe he won't like me. Maybe I won't get the job. It won't work out,'" Sandberg said. "And he said to me, 'Why are you going to take this job and make less than any man would take?' And that was motivating. And it turned out that I was able to negotiate." Sandberg is ambitious, as evident in her successful career. But she said she recognizes that unlike many women, she is "lucky" and has had the resources to advance her education and career.
In the book, she shares her views about flextime, childcare and suggestions for policy reform. She also laments that even young girls feel they often must choose between likeability and leadership, as revealed by case studies.
"Institutional policies are hugely important. But the other piece, which is what Lean In focuses on, is that what we can do for ourselves in breaking down stereotypes is equally important," she said. "Unless we get all of those, we will not change the trajectory for women in leadership."
Though she said she has no sights on public office, she hopes men and women will discuss further the cultural and institutional underpinnings that may be holding some women back from leadership roles.
One person she hopes runs for the highest office in U.S. government again is Hillary Clinton. When reflecting on the 2008 presidential election, Sandberg laments the fact that Hillary's "likeability" was critically pegged to her clothing and appearance, much more so than her male opponents.
Sandberg said she hopes her 4-year old daughter will one day not ask her why all the past U.S. presidents are male.
"I believe if we had half our companies and half our countries run by women, and half our homes run by men, things would be better," she said. "We know our companies would be more productive. If you use the full talents of the population, you're more productive. We know our homes would be happier."