Former Buffalo coach Marv Levy coached the Bills through the 1997 season at the age of 72. Nearly a decade later, Levy returned to the organization as general manager from 2006-07 while in his 80s. At the time of his GM stint, Bill Belichick fielded questions about Levy's longevity, and the Patriots coach famously responded by saying he had no interest in coaching into his 70s.
Fast-forward 15 years and here's Belichick at the age of 69 and still going strong. Few of his quotes have enjoyed the staying power as his thoughts on Levy have, but it'd be safe to say that a lot has changed in the coach's life since he uttered those words.