Among her many achievements, philanthropist Melinda Gates was the first woman to have given away more than $40 billion.
As co-chair of the Bill and Melinda Gates Foundation — alongside her husband, Microsoft co-founder Bill — Gates has been part of a movement that has supported work in more than 100 countries that face challenges in education, poverty, hunger and health.
Consequently, heading such an organization means needing to hit milestones and potentially even exceed targets.
In an interview with CNBC, Gates said she is particularly proud of what the private foundation had achieved in improving world health.
"The work that we've done in vaccines, to really get vaccines out to hundreds of millions of children," Gates told CNBC Meets when asked about what her proudest moment of the foundation had been so far.
"There are 3 million children alive today because of those vaccines and when we started in this work, there was you know a 20 or 25-year lag between when a vaccine would come out in the United States and when it would get to the developing world. Even when it got there, it wasn't all the right strains that they needed."
She added: "Even in this family planning work — we've only been at it since 2012 — but there are over 20 million women who voluntarily have gotten family planning access, who wouldn't have had it otherwise."
Driven by ideals surrounding equality, the Bill and Melinda Gates Foundation works to assist people worldwide to lead "healthy, productive lives" — from fighting extreme poverty and stamping out hunger in developing countries, to providing education opportunities in countries such as the U.S.
Gates is delighted by the number of lives saved by vaccines, but the foundation still has goals it wants to achieve by the end of the decade.
By 2020, it aims to have prevented more than 11 million deaths, 264 million illnesses and 3.9 million disabilities by providing sustainable vaccine coverage and support.
Another area that the Gates Foundation is focusing on is contraception and family planning. It has set a target of delivering high-quality services and supplies to an additional 120 million women and girls in developing countries by 2020.
When it comes to her proudest moments on a personal level, Gates recalled a time she met a woman called Marianne in the slums of Nairobi, Kenya.
"When we were all finished talking about the importance of contraceptives, (Marianne) finally summed it up — and she had a beautiful baby girl in her arms — and she said 'I want to give all good things to this child before I have another one.' And I thought, 'Isn't that what parenting is all about? That we all want every good thing for our child, before you have the next one.'"
"We all want the best for our kids. Everyone's about the next generation. 'How do I make sure my kids get a great start in life and a great education?'" said Gates.
"And it's those universal truths that I think keep me coming back to this work, and the women that I meet all over the world."
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