It's an unusually warm january day in Los Angeles, and Jonathan Goldsmith looks pretty uncomfortable in a turtleneck, wool sweater, thick black pants and ski boots.

But when the cameras roll he is instantly cool, smiling and laughing as if he's at a cocktail party - not a TV-commercial shoot in a back lot at Universal Studios. With only a thin cable for a harness, Mr. Goldsmith skids down a 15-foot-high wooden structure filled with fake snow to look like a ski jump. He nails it. "Like the wind," he says at the bottom.

After all, when you are The Most Interesting Man in the World, everything comes easily. Or at least it looks as if it does.

In reality, Mr. Goldsmith's stardom -- and the rise of the Dos Equis beer brand he represents -- did not come easily. Both are success stories decades in the making. Mr. Goldsmith, 73, a longtime journeyman actor but never a star, is now so big that Michael Jordan recently asked to have his picture taken with him.

And Dos Equis, once a low-profile brand sold mostly in Texas and California, has become the country's sixth-largest imported beer. The surge is largely attributable to the James Bond-meets-Ernest Hemingway character Mr. Goldsmith plays, who is so revered that , as one ad says, "if he were to pat you on your back, you would list it on your résumé."

As the campaign enters its sixth year, Ad Age sat down with Mr. Goldsmith and the Dos Equis team to talk about their success while getting a behind-the-scenes look at the production of new spots that will roll out this month. With a few new wrinkles that include exposing The Most Interesting Man's "dark side," the commercials seek to maintain momentum for Dos Equis, which gained 15.4% in U.S. shipments last year, vs. 2.7% average growth for the top 10 imports, according to Beer Marketer's Insights.

The breakthrough has provided a much-needed star brand to complement Dos Equis importer Heineken USA's flagship Heineken lager, whose shipments are down 20.5% since 2006, according to Beer Marketer's.

In the beginning, Dos Equis had no idea it would have such a big hit on its hands. The campaign's first ads were originally aired in a few select markets in the West. And Mr. Goldsmith certainly didn't know what he was getting into the day he auditioned for the part in 2006.

"Basically it was just a cattle call," he said. "I got into the room, and there were hundreds of people and a big crowd waiting outside, and everybody looked like Juan Valdez. And I said "This is crazy -- they are not looking for me.' I went in when it was my turn and all I could think about was "My God, I've got to move my car by 4 o'clock or I'm going to get a massive ticket. " "

What Dos Equis was looking for was a lead actor for a campaign that would break the beer-advertising mold. While so many spots featured fancy cars, hot babes or exotic locations, the Dos Equis team discovered that "more than anything else, [drinkers] really wanted to be seen as interesting by their friends," said Senior Brand Director Paul Smailes.

Rather than cast a young actor, Dos Equis went with an older, worldly protagonist. The logic was that the target of young men would not "see him as a threat or as a reminder of accomplishments they hadn't achieved yet," Mr. Smailes said. He "needed to be someone to work toward, vs. a mirror of themselves."

Mr. Goldsmith is a self-described Russian Jew from New York who's a bit of a hypochondriac. He had pretty much given up on Hollywood by the time of that tryout, turning his attention to business ventures such as logging and car washes. I first met him at the office of Dos Equis' production company, Radical Media, where Mr. Goldsmith had arrived for a wardrobe test with a gym bag and his third wife, Barbara. He wore a green windbreaker and an earring he'd bought at a drugstore for $5. Unassuming at first, Mr. Goldsmith commands the room once he starts talking, full of same charm and charisma as the character he plays.

He first got into acting after being "asked to leave" New York University, where he partied too much and had a fling with one of his professors, he said. His psychiatrist introduced him to a stage director who told him to enroll in acting school at New York's Living Theater. His first scene was an improvisation. "I got applause for the very first time in my life," he said. For a guy who was "never successful at anything," he said, that was enough. He was on Broadway in no time.

Convinced that he could make it in Hollywood, he packed up his old Volkswagen and headed West. Once there, however, "nothing happened," he said. So to make a living he drove a garbage truck filled with industrial waste. He always had a blue dress-suit at the ready in case he landed that elusive acting interview.

He finally got one. One of his big breaks was a role on the popular TV western "Gunsmoke." But the script ("Kyle vaults on the horse and gallops into the night") posed some serious problems for a kid from the Bronx. "Fuck me, I couldn't ride a horse," Mr. Goldsmith recalled. Practicing on an aging, lethargic one, he said, "I promptly got up on the wrong side. ... The horse threw me into the mud ... and that 's how my career began."

But he kept climbing back in the saddle and eventually appeared in the series 16 times. He parlayed that work into roles on other hit shows in the 1960s, "70s and "80s, including "Bonanza," "Hawaii Five-O," "Knight Rider" and "Dallas." He was "always the wise guy," he said, or the one being shot or killed. But he was maimed by the best, as in the 1976 movie "The Shootist," with John Wayne firing at his head. Mr. Goldsmith was pelted repeatedly with so many blood capsules that the director spurred him on with, "Everybody who got shot in the head by John Wayne made it big-time," Mr. Goldsmith recalled. Laughing about it now, he added, "40 years later, here comes Dos Equis."

When Dos Equis came calling, the beer, like Mr. Goldsmith, was not a star, playing more of a supporting role for Heineken USA. The Most Interesting Man campaign was created to move beyond conventional Mexican imagery. The brand cast a wide net for its lead, searching for a mature, experienced actor who wasn't too recognizable. (His wife, then only his agent, got Mr. Goldsmith into the audition.)

"All I knew was they were looking for actors that had improvisation [skills]," said Mr. Goldsmith. He was fed only one line to say at the end: "...And that 's how I arm-wrestled Fidel Castro."

With nothing to lose, he based his character on Fernando Lamas, an old sailing buddy. It was perfect. "Jonathan not only looked the part but had a specific bravado that came across beautifully on camera," Dan Fried, a former producer at Euro RSCG, said in an email.

Mr. Goldsmith, as it turns out, shares traits with The Most Interesting Man. For years he lived on a sailboat docked off the California coast. He says he once saved a girl from drowning and rescued a man caught in a snowstorm on Mount Whitney. He knows where to find a great conch salad in the Bahamas. And yes, he doesn't always drink beer, preferring a martini or Scotch.

The campaign went national in 2009 and quickly found its way into pop culture. Dos Equis sales soared, more than doubling between 2006 and 2011 to more than 15 million cases, according to Heineken USA. The campaign has stuck to the same formulas even as it has passed through multiple brand directors and agency executives.

One series of ads shows flashbacks of The Most Interesting Man's sometimes death-defying and always quirky feats spanning the 1960s to the 1990s. Grainy scenes show him parachuting out of an airplane in a boat, for instance, while a narrator intones one-liners such as "He's won trophies for his game face alone." The other set of ads are simpler, featuring the Man giving advice on topics such as speed-dating: "I assure you, most women would not consider speed a virtue."

The Man's feats (such as "bowling overhand") are offbeat but not impossible, but the laughs aren't cheap. "We don't want to go for the sophomoric, cliché humor that is sort of the staple of the [beer] category," Mr. Smailes said.

Mr. Goldsmith described his character as "every guy's fantasy," whose old-world charm and "rustic elegance" contrast with today, when "the days of gentlemen and chivalry are long since gone.

"Although he lives well, this man has the accoutrements of wealth and there is also an elegance of relationships," the actor added. "He hangs out with pygmies. He's a teacher. He's a sage. He's a shaman. He's a fantasy. He's an illusion of things past."

The campaign's also looks to push boundaries. Last year, this led to some trouble, when a billboard that read "Approach women like you would wild animals, with caution and a soothing voice," drew complaints from women's groups and was pulled.

On set, the Radical Media crew keeps a relentless focus on details. I watched them shoot a scene set in the 1980s, in which the Man happens on a ski jump while out for a winter walk. So he decides to give it a try.

Multiple cameras are used, including a vintage Bolex handheld used to give scenes a "found footage" look. In a sequence that will last only a couple of seconds in the ad, the Man casually hands his cigar and watch to a couple of skiers dressed in ugly blue ski suits before he heads down the jump.

In take after take, Director Steve Miller yells out instructions. "Big laugh," he instructs Mr. Goldsmith, who instinctively complies. The joke, Mr. Miller later explained, is to put him in "serious or life-threatening situations, and he just throws a laugh in there. ... It's a great contrast."

For scenes set in the "60s or "70s, a younger actor, Claudio Marangone, replaces Mr. Goldsmith. On the day I watched, he was playing the Man in a scene set in 1970s-era Spain in which he runs not with the bulls but against them. With cameras shooting from above, two live bulls are unleashed directly at Mr. Marangone. After a few rounds, Mr. Miller seems satisfied. But a crew member shouts, "My cable got cut by the cow." The video feed was lost. So they shoot again.

This year, for the first time, a few spots will run for Dos Equis Amber, a dark lager that accounts for about 30% of brand sales. "They say having a dark side will lead to no good. I certainly hope so," the Man says in one ad.

One thing people won't see is Mr. Goldsmith making public-relations appearances, or showing up in TV programs or movies, as the Most Interesting Man. Heineken USA has said it has turned down plenty of offers because it does not want the character to overshadow the brand. "You want to make sure the awareness is around the brand, instead of the awareness of the character," said Kheri Holland Tillman, VP-trade marketing and sales strategy.

Even so, it seems undeniable that the Man is almost single-handedly fueling sales. Although that 's a testament to the power of advertising, it also applies pressure to keep things fresh. Much of that responsibility falls to Lee Garfinkel, Euro RSCG's chief creative officer-global brands, who joined the agency about a year ago. His writing team brainstorms more than 400 punch lines a year and whittles the list down to about 30 for TV and radio.

The campaign will undergo "small evolutions," Mr. Garfinkel said. For instance, the Man this year will deliver his famous parting shot -- "Stay thirsty, my friends" -- from his manor rather than a bar banquette. Where he lives is still a guarded secret.

Meanwhile, Mr. Goldsmith has docked his sailboat for good and moved to a quiet farmhouse in Vermont. He is , without a doubt, a full-fledged celebrity, recognized routinely by strangers who aspire to be his character. All because of a beer ad. "I always looked down on commercials." He said he never wanted to be in them. But "it's the best thing that ever happened to me in my life."