Huh.

[Gary] Gilmore, the notorious spree-killer, uttered the words “Let’s do it” just before a firing squad executed him in Utah in 1977. Years later, the phrase became the inspiration for Nike’s “Just Do It” campaign.

“I like the ‘do it’ part of it,” Mr. Wieden, a co-founder of Wieden & Kennedy, says in the film, recalling the moment it dawned on him to use the phrase. “None of us really paid that much attention. We thought, ‘Yeah. That’d work,’ ” he says, adding, “People started reading things into it much more than sport.”