What is an entrepreneur?

"A person who organizes and operates a business or businesses taking on greater than normal financial risks in order to do so," is the dictionary definition.

But in practice, it's much more than that.

It means going out on a limb, working long hours with little sleep, often risking your life savings, a steady income, health insurance and other life amenities in pursuit of a dream.

Houston is dominated with such dreamers who put their plans into action. Being a entrepreneur seems to be part of the city's DNA. Perhaps it stems from the wildcatter days, where prospectors staked their futures on the search for oil and, in the process, lost and won several fortunes in one lifetime.

Nowadays, a variety of factors makes Houston an entrepreneurial hotbed, says Ken Jones, associate director of the Wolff Center for Entrepreneurship at the University of Houston.

A large port handling a booming import/export business, a history of energy exploration and thriving medical center all provide opportunities for the creative class. "That's a pretty nice triangulation to hang your hat on," Jones says.

The diversity of the city offers a welcoming attitude for those who want to take a chance. In addition to newcomers, the entrepreneurial spirit draws those who took early retirement, got bored and started figuring out how to reinvent themselves along with those who got laid off and are coming up with new ideas because they don't want to leave the city they love. (Ironically, some of the world's best ideas take place during a recession.)

Jones also believes there's an inward focus in Houston right now, where a desire to create big things is part of the city's fabric. "We're not making our money and leaving. We're making our money and staying," he says.

With $250 and big dreams, Danny Arnold opened a sports training facility in Houston 14 years ago. Now he owns Plex sports training centers in Sugar Land, Katy and Willowbrook that have become the go-to place for an impressive roster of pro sports stars, including Lance Berkman, Julius Peppers, Kevin Kolb and the Lopez siblings, along with everyday Joe's and Jane's seeking a place to get fit.

In the first of the CultureMap series Profiles of Innovation Arnold tells videographers Douglas Newman and John Carrithers about the entrepreneurial spirit that led him to think big and why the exercise business in Houston will grow and prosper.

"I'm leading a charge for an industry that remains untapped," he says.