Sara Blakely’s bottom line is taking a hit — for a cause.
The 42-year-old Spanx founder — crowned the world’s youngest self-made female billionaire by Forbes in 2012 — has signed the Giving Pledge, “ a commitment by the world’s wealthiest individuals and families to dedicate the majority of their wealth to philanthropy,” according to the group’s Web site.
“Whether it’s boosting their butts or their businesses, I’m passionate about helping women,” Blakely tells PEOPLE. “By joining the Giving Pledge, I’m looking forward to learning the most effective way to pay my success forward and really make an impact.”
The pledge was founded by Bill and Melinda Gates and Warren Buffett and has thus far enlisted 114 commitments from various billionaires, including Facebook founder Mark Zuckerberg, New York City mayor Michael Bloomberg and British business magnate Richard Branson.
In an interview with PEOPLE last year, Blakely — whose nonprofit foundation has given more than $18 million to women in need — spoke about her desire to share her good fortune.
“From a young age I always had an awareness and gratitude for being a woman born in America,” she said. “So the blessing is like, ‘Wow, I can do so much with this. Money can create change, it can build things, it can help people.’”
Tell us: What do you think of Blakely’s decision to give away most of her wealth to good causes?