• GM CEO Mary Barra and former IBM CEO Ginni Rometty joined CNBC's Leslie Picker at the CNBC Councils: Leaders' Library on Monday in New York City.
• The female CEOs shared a wide-ranging conversation at the inaugural Leaders' Library event.
• They discussed the examples set by their own mothers during childhood and their professional journeys, from downplaying their gender to embracing their role as female business icons for other women today.

GM CEO Mary Barra and former IBM CEO Ginni Rometty have a lot in common, from overcoming early obstacles in childhood to rising through the corporate ranks to become CEOs of blue-chip, century-old companies. They are professional peers, and friends, and were brought together for the inaugural CNBC Councils: Leaders' Library, as a result of Barra's recommendation of Rometty's book, "Good Power."

The wide-ranging conversation held on Monday in New York City with CNBC's Leslie Picker covered how Barra and Rometty embody power in the workplace, leading companies through transformations, and bridging economic and social divides in the U.S. In addition, the business icons discussed how their own view of being a "woman" leader has changed over the course of their careers.  

Often being the only women in the room in manufacturing and technology engineering roles at major corporations led them to shy away from gender as they climbed the corporate ladder. But now, as women at the top of their respective fields, Barra and Rometty's thinking on the topic of female leadership has evolved.

Here are a few highlights from the conversation.  

Overcome your hesitation to lead with 'woman' 

It may seem logical that with so few women in high-profile CEO roles — even today it is only about 10% of the Fortune 500 and S&P 500 — female CEOs might be inclined to highlight gender as part of their success, but both Barra and Rometty say they shied away from leading with gender early in their careers — or even mentioning it. They now say that was a mistake. They believe leading with "woman" is critical to showing the way forward for the next generation of leaders in a world where the gender disparity in the C-suite remains wide.

Rometty said she began embracing her identity as a woman in the workplace when people began recognizing her as a role model. "People can't be what they can't see. And I finally realized that I was being selfish by saying, 'no, no, don't look at me for being a woman, don't ever look at me for this.' Then I finally started to embrace it. ... I talk about our differences, that we can leave a memory and a mark," Rometty said. "It's worth noticing that you notice there's not many of them."

Barra ultimately had a similar awakening. She rose from the ground floor in manufacturing, and said in early roles it was easy for her to overlook being the only woman. But as she climbed to the C-suite, comments on her identity increased, a situation that made her uncomfortable. Barra recalled asking people, "Can we talk about something else, because I'd like to think I got here because of my skills and abilities and contributions, not just that I'm a female."

Barra changed her perspective as she witnessed the impact her identity had on other women in the workplace. "When I got the CEO job, people would come up to me, and they'd say, 'So you're the first female CEO of an auto company?' ... But then I had the same situation [as Rometty], when someone came up to me after a meeting or something and said, 'You know, my daughter is now working hard at math and science in middle school, because she wants to be like you.' And then I'm like, okay, I get it. I get it."

Embrace your upbringing, motherhood 

Barra and Rometty both take pride in fighting against the "motherhood penalty" in the professional world. Motherhood can hamper perceptions of competence and result in lower pay, promotion, and workplace respect.

Barra, who now has two grown children, said a lot of people assumed she would stop working when she shared that she was going to have a child. This expectation helped her to realize the importance of being a role model and mentor.

"I am a mom, I had two children, I had to juggle both. But so often, I see women saying, 'Someday I'd like to have kids, so therefore I can't do this.' And I'm like, wait a minute, you know, you're 23. And you're already saying no to things? You can do both. ... I had such a wonderful mother who encouraged me. I wasn't facing the 'I cannot, I can't do that, because I don't see anyone who looks like me who is' ... I had this phenomenal mother who just raised me to believe if I worked hard I could do and be anything so early on."

Rometty said she was raised by three generations of women who endured significant hardships, including a single mother — her father left the family when she was still young — and each provided models for overcoming challenges. "It does prepare you to have the courage to endure things," she said.

Rometty's mother, in particular, helped pull her family out of poverty, and Rometty said she had "power even when she had nothing." 

Rometty believes that workforce culture must change to build more confident, thriving female executives. "So much of my belief of why you don't see as many women [in top roles] has to do with if you can't keep them in the workforce," Rometty said. "They reach a certain point, whether it's children, family, whatever it is."

She added that beyond the formal programs she is involved with to encourage more female leadership, a major way to get into the workforce if they've left is having them see "women in our positions."

Be confident in your workplace qualifications 

When Rometty would be offered better jobs early in her career, her first instinct was to say no to the job, "because I was afraid I couldn't do them."

She recounted one instance in which she was offered a job, "and I said, 'let me go home and ask my husband.' The guy looks at me like, okay, that's kind of a weird answer. And I went home and my husband says, 'Do you think a man would answer it that way? I've watched this over and over, every time you take a new job, you're talking about everything you can't do... and then in six months, you're bored.'"

"Growth and comfort will never coexist," Rometty said, adding that a core idea of her book is reframing risk as a learning tool. "Every time I feel at risk and nervous, I'm learning. So this is good. It would let me take on riskier and riskier stuff. ... this isn't a bad ending. I'm gonna learn something. ... It resonates with all humans, but I do hear it resonate a lot with women."

This widespread fear of rejection and risk also manifests for women in the recruiting process. "If there's 10 requirements in a job, a woman will look at and say, 'Oh, I only have nine of the 10. I can't even apply for the position, where a man will have five or six and go for it," Barra said. 

In the workplace, Barra said that women, "Don't raise their hand, because they're a little, they're a little unsure. And then someone will eventually say what they were thinking. And then no one knows."

Barra advised young women in the workplace to "have a point of view. And it's okay if it isn't what the group decides to do. You need to be heard, you need to have a voice. ... I think one of the most important things that I've encouraged women is, is to go for it."

To learn more about CNBC Councils, visit cnbccouncils.com.

Correction: Ginni Rometty is the former CEO of IBM and author of the book "Good Power." An earlier version of this article misspelled her name.