When Zac Efron signed up to play a still-living person, he knew there would be challenges.

What he didn't know was underneath the heroism of that real-person, there was a kind man honored to have his story told, which made Efron all the more honored to portray him.

The movie The Greatest Beer Run Ever, streaming on Apple TV, is based on the memoir of the same name by John "Chickie" Donohue, who went from the United States to the jungles of Vietnam in order to give his friend serving there a cold beer and a pat on the back from home.

"It's one of those unbelievable real-life scenarios that you just can't believe a guy got himself into," says Efron. "It's a beautiful story about human nature, love and a really difficult war and time in history."

Donohue was on set during pretty much most of the filming, but despite the fact he knew nothing about show business, and nothing about Zac Efron, here was this Hollywood A-lister treating him with deference.

"Instinctively I said, ‘I like this guy!" Donohue told People. "I had no mission to teach anybody anything. My mission was simply to let the guys over there know that we truly, truly supported them."

Donohue added he had already seen the movie twice, and feels Efron played him better than he did when he was actually going to deliver beer to soldiers in Vietnam.

The then-26-year-old merchant mariner and New York native boarded a cargo ship bound for the war, and ended up traveling all the way to the front lines.

For Efron, the connection he made to the real-life hero was the biggest reward of all the effort that involved location shooting in terrible weather, and having to maintain a handlebar moustache the whole time, adding he just wanted to turn in a performance "Chickie" could be proud of.

The film was released on Apple TV September 30th.

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