David Duffield cofounded not just one, but two successful enterprise software companies after age 40: PeopleSoft and Workday. He resigned as chairman of Workday in April 2021; he cofounded the HR and finance software firm in 2005 and took it public in 2012. Duffield cofounded PeopleSoft at age 47 in 1987 and sold it to Oracle for $10.7 billion in cash in 2005. Duffield started his first business at 28. As a child, he mowed lawns but says his most impactful job was a systems engineer at IBM after college. He has given $345 million to Maddie's Fund and has doled out another $400 million to, among others, his alma mater Cornell, as of June 2019.