Former fashion designer Cindy Meehl learned a lot while making Buck, a surprisingly multilayered documentary on real-life horse whisperer Buck Brannaman. On a professional level, she walked away from the two-year-project understanding what it was to be a filmmaker. Before stepping behind the camera, Meehl had never directed; her admiration for Brannaman’s way with animals motivated her to take up the challenge.

On a more intangible level, the Connecticut-based mother, wife, and long-time admirer of man’s other best friend learned something valuable to apply to her everyday life, namely that there’s no point doing something if you’re not willing to commit to it. Powered by word of mouth at the 2011 edition of the Sundance Film Festival, Buck —opening Friday in Vancouver—has turned into a hit, the fallout from that teaching Meehl that, sometimes, directing a movie is the easy part of the job.

“Because we did well at Sundance, it’s taken off like a rocket,” says the easygoing director, on the line from New York City, where she has a speaking engagement. “So there’s been tons of travel, which is very exciting, but it’s almost been a much faster pace, in a weird way. I think it’s continuing to do well because I really just don’t stop. Buck really helped teach me that. He’s like a machine that just goes and goes and goes. Some days I’d like to take off and have a rest, but then you’ll look at the alternative and think, ‘God, this is amazing, because people are really being helped by this film.’”

Consider that a head’s-up that Buck might be about a quiet-spoken old cowboy with a knack for calming down the most ornery of horses, but the story doesn’t stop there. Stepping back and looking at the larger picture, the film touches on the importance of showing compassion toward our fellow humans, on the need to break cycles of abuse, and on how nurture can play a far greater role in fate than nature. All of this springs out of Brannaman’s back story.

Buck takes us back to his beginnings in Montana, where, pushed hard by an abusive father, he and his brother Smokie became child prodigies on the rodeo circuit. Famous for trick roping, the siblings would eventually appear everywhere from television talk shows to commercials for Corn Pops cereal. They would also, after their mother died, end up mercilessly beaten by their alcoholic father. In one of the movie’s many moving moments, Brannaman talks of being repeatedly hauled out of bed at 2 in the morning as a child and forced to sit at the kitchen table by his enraged father. He once ran out of the kitchen in the night, only to find himself in below-zero temperatures, barefoot and in pajamas. Rather than head back inside, he climbed into a straw-lined barrel with the family dog.

As difficult as such memories might be, Meehl reports that Brannaman put up no barriers when the camera was rolling.

“He talks all day long from the back of a horse into a microphone,” she says. “A lot of people ask me, ‘Is he really shy about opening up?’ Maybe at one point in his life he was, but not now. He was very comfortable talking about any subject thrown at him.”

But where Brannaman looks happiest in Buck is when dealing with horses, his philosophy being that there’s no need to break them Old West-style. If his own story taught him anything—he was raised by loving foster parents after being removed from his father’s care—it’s that relationships are built on kindness, not abuse and intimidation.

Brannaman is now an in-demand legend among horse owners, to the point where he’s on the road nine months of the year, criss-crossing North America. The film finds him giving clinics in the kind of gorgeous, wide-open spaces that make one think about hauling up stakes and moving to the country. Time and time again, he’s shown connecting with animals that are thought to be untamable. That sends a valuable message: that no creature on this Earth is to be given up on, whether it’s a frightened horse or a kid who has been dealt a bad hand.

“Buck’s past helps you understand why, when you take him your rescued horse that has been beaten and abused, that you don’t have to tip-toe around the subject,” Meehl says. “He knows what that’s like, and he understands that it’s much more important to give that animal some sense of worth. He’s not giving horses excuses or coddling them—that doesn’t serve them any purpose. It’s much better to give them self-esteem.”