On a rooftop parking lot, with temperatures in the chilly low 50s, a crowd of all ages shimmied and shook, sweated and smiled as DJ Francis played an eclectic mix of dance music. But this wasn't just another wild South Florida party. It was a special Zumba class for charity, led last month by the creator of the global craze, Alberto "Beto" Perez. The charismatic Colombian in cargo pants — who has become a rock star in the fitness world — climbed onto the roof of a Chevy minivan that doubled as a stage. He demonstrated salsa steps, the merengue march and many other Latin-inspired dance moves — all while also cuing the drummer and the bongo player. For an hour, 75 of his adoring fans — and even the minivan — moved to the beat. "Everybody loves it; everybody has fun," Perez said while posing for pictures with his Zumba faithful, some of whom had traveled from as far as Canada. Two days later, Perez flew to New York to appear on the TV morning show "Live! with Kelly." "You must be so rich by now," host Kelly Ripa gushed to Perez, 41. Perez's Zumba classes, with the motto "Ditch the Workout, Join the Party," were strictly a South Florida phenomenon 10 years ago. Today, Zumba Fitness has become the largest branded fitness program in the world, with about 12 million people taking Zumba classes weekly at 110,000 locations in at least 125 countries, according to company spokeswoman Allison Robins. The private company won't reveal information about the company's finances or its net worth. But at a time when most of the world is struggling economically, Zumba Fitness' empire appears to be flourishing. It is doing so on the strength of a growing army of certified instructors who spread the Zumba gospel to such distant outposts as Iceland, Papua New Guinea, Nepal and even Afghanistan — at the Kabul Community Center. Many fitness crazes have come and gone. Staying power is tough in the ever-evolving fitness industry. John Figarelli, founder of the National Fitness Hall of Fame Museum and author of "The History of Fitness: Fads, Gimmicks and Gadgets," said: "I think the owners of Zumba did a great job of getting it going from a business standpoint." Zumba Fitness does not charge gyms to carry its classes. Instead, it trains instructors and gives them the license and use of the trademark if they join the Zumba Instructor Network. "We're helping the instructors to become entrepreneurs and make a living out of it," said company co-founder Alberto Aghion. Exercise as a business It's a sound strategy, said Figarelli, whose book covers 100 years of working out, from 1900 to 2000. "Most group-exercise instructors will just go with the next popular class. But if Zumba is your business, instructors will stay with that." Ensuring instructors are successful has become the company's main mission. "We have three people who all they do is call up gyms all day and try to find instructors employment," said company co-founder Alberto Perlman. The company has made Zumba instructors easy to find, with a worldwide listing that includes all of their network instructors' classes regularly updated on the company's website. Instructors also receive new music and choreography about every two months. The music department now creates music just for Zumba classes, with original songs that include "Zumbalicious," "Que Te Mueve" and "Caipirinha," which was a No. 1 song in Israel. Zumba Fitness makes its money on its instructors academy, instructors courses, monthly fees from instructors in its network and on all its brand merchandise. The company has built its own line of hip, colorful clothing and footwear, workout DVDs, two video games, original music and a lifestyle magazine, Z-Life. This was not the business model when Zumba Fitness was founded in Aventura, Fla., in 2001 by the "three Albertos" — creator Perez and boyhood friends Perlman and Aghion, both entrepreneurs in their mid-20s and natives of Colombia. The trio's original plan was simple: produce VHS workout tapes of Perez's popular South Florida classes to sell around the country on infomercials. An inspired ad-lib Perez fell in love with dancing at age 7 by watching a VHS tape of the 1978 movie "Grease," starring John Travolta. At age 16, he was teaching aerobics classes for $1 an hour. One day, he forgot his prepared music. All he had in his backpack was a cassette tape of merengue and salsa music he'd recorded off the radio. His morning class was full of moms who had dropped their kids off at school. "I can't say, 'Hey sorry, I forgot my music,' " Perez said. "I say to the people, 'I have a new class I prepared for a long time.' It was not true. I improvised for one hour." The moms loved the dancing exercise. Perez turned it into a regular class in Cali. He soon moved to the Colombian capital of Bogotá, where he continued those classes and became a choreographer for Sony Music and Shakira. In 1999, Perez came to the United States for the first time. He pounded the pavement on South Beach, going from gym to gym. Nobody was interested in this new dance exercise class by a guy who couldn't speak English. On his fourth trip to Miami he landed a job at the swanky Williams Island Spa in a development where several Colombians lived. Some had even taken classes with him in Bogotá. Within a year, Perez was in demand, teaching 22 classes all over South Florida. At the same time, Perlman and Aghion were looking for a new business venture after the dot-com bubble burst, bringing down their Internet company, Spydre Labs, an incubator for Internet startups related to Latin America. Enter Raquel Perlman. While Alberto Perlman was telling his mom about how badly he was feeling for laying off people, she was telling him about how happy she was taking Perez's classes, where were then called Rumbacize. "You should meet Beto and maybe start a gym together," she told her son. "He's the talk of Aventura." Perlman watched a class and was reminded of people having fun at a nightclub, but without the drinking and pickup lines. "Beto, have you heard of Billy Blanks' Tae Bo? Why don't we do VHS tapes and sell them on television?" Perlman said he told Perez. In August 2001, they and Aghion founded Zumba Fitness. To create a demonstration video to show investors, the three stayed up all night laying down boards to create a dance floor on the beach outside a Sunny Isles hotel. About 200 of Perez's students paid $20 each for the class, raising an additional $4,000. When the infomercial began running on TV, people rang the call center in Ohio to buy the videos, and a few also asked how to become Zumba instructors. Those callers were forwarded to Zumba's office — at Aghion's home. After a few 2 a.m. wakeups, Aghion realized this was another business opportunity. Zumba Fitness also has greatly benefited from Internet advertising and social media. Many people discovered Zumba via YouTube videos. Zumba Fitness started a Facebook page about a year ago and now has more than 3 million fans. Zumba is mentioned every 11 seconds in social-media platforms, Robins said. It's not clear yet if Zumba will have a long shelf life or be added to the long list of exercise fads, said Walter R. Thompson, professor of exercise science at Georgia State University. He'll watch to see how it fares over the next few years in a worldwide survey that ranks fitness trends. "I hope it stays around," he said. "It's motivating a lot of people to exercise."