“Improvise, adapt, overcome” is an unofficial motto of the US Marines. The earliest record that the word researcher Barry Popik found is the 1986 film Heartbreak Ridge. Clint Eastwood plays a Marine gunnery sergeant. He tells his men: “You’re Marines now. You adapt. You overcome. You improvise.”
Some writers say Marines used the words long before the film. Popik found no printed evidence for that. By April 1988 Jack Clark was quoting it: “It’s like Clint Eastwood said, ‘You’ve got to improvise, adapt and overcome.'”