Since the Creative Revolution in the 1960s, industry heavyweights like David Ogilvy and George Lois have touted the proverbial “big idea” as the driving force behind the world’s greatest advertising campaigns.

They weren’t wrong. But every great campaign—hell, every great creative endeavor—begins with a microscopic thought or insight. Isaac Newton allegedly conceived the theory of gravity after being hit on the head with a falling apple. Star Wars came to be because George Lucas wanted to put a samurai in space. After a delayed train ride, J.K. Rowling felt inspired to pen a series of books about an academy for adolescent wizards.

The process in advertising is no different. Even the brightest visionaries in this business can’t summon creativity at will. Brilliance takes time. The big idea emerges only after a smaller one is hatched.

One such idea was dreamt up for Nike in the 1980s. The story goes that Gary Gilmore, an inmate on death row, was to be executed by firing squad. Just before they fired, he said, “Let’s do it.” Dan Wieden, co-founder of the powerhouse Wieden & Kennedy, twisted this brave quip to create perhaps the most iconic slogan in advertising history. Today, “Just Do It” is recognized the world over and has cemented Nike as the most respected name in sports. But it didn’t happen until a long six years after the agency added the brand to its roster of clients.

Even Old Spice cycled through different concepts, taglines and commercials before finally landing on its wildly successful “The Man Your Man Could Smell Like” campaign, a trying three-year process. In fact, before Isaiah Mustafa swept the world off its feet with his mythical machismo, Bruce Campbell had a brief and middling run as the original Old Spice spokesman. More proof that big ideas don’t materialize out of thin air.

Instant gratification is a myth in nearly all creative endeavors, including advertising. The process is ugly and painstaking—a reality many designers, writers and developers know all too well. Only after putting in the work can they proudly say they’ve built something memorable.

The most successful of them know that catching the elusive white whale of an idea means starting with the small fry.