--- Mohammed Ali, via the Ear Hustle, Episode Two. The quote is given near the end, from about 25:50.
Quote Investigator has the backstory. The first instance was a 1974 quote in a UPI wire story, “If a man looks at the world when he is 50 the same way he looked at it when he was 20 and it hasn’t changed, then be has wasted 30 years of his life.” By November 1975 he'd streamlined it to, The man who views the world at 50 the same as he did at 20 has wasted 30 years of his life.”
