The athlete-turned-entrepreneur model is nothing new. From the ice skater who founded a world-spanning nonprofit to the tennis pro who started her own candy company, athletes are finding that what they learned playing competitive sports prepared them well for the challenges and glory of business entrepreneurship.

Maria Sharapova

Athletic Career: Sharapova remains the third highest-ranked tennis player in the world, according to the Women's Tennis Association. She won her first adult tournament in 2003 and won Wimbledon a year later. In 2005, she was ranked number one by the WTA, and has spent a total of 21 weeks holding that position.

Entrepreneurial Venture: "The whole candy line was about doing something unexpected and different," Sharapova says about Sugarpova, which she founded in 2012. Although she had already signed endorsement deals with fashion and athletic labels, this was her first experience running a business of her own. In the first year of business, the brand, with flavor names like Smitten and Flirty, expanded into seven countries, netted a 120 percent return on her initial investment, and earned Sharapova a spot on CNN Money's list of the top 10 female celebrity entrepreneurs.

Rick Mirer

Athletic Career: After a four-year run at the University of Notre Dame that earned him a spot in the Indiana Football Hall of Fame, Mirer was the second overall pick for the 1993 NFL draft. He started with the Seattle Seahawks, where he set all-time rookie records and became the third quarterback in the history of the sport to start in every game of his first professional season. For 12 years, he served as a regular starting quarterback for a total of seven different teams before retiring in 2004.

Entrepreneurial Venture: Near the end of his professional run, Mirer played for the San Francisco 49ers, where he became enamored with the California wine culture. Of his time in Napa Valley, he says, "It was just a totally different way of spending time ... it felt really good." In 2008, he started the Mirror Wine Company, which grew from 500 cases to over 1,000 in the first year.

Kristi Yamaguchi

Athletic Career: Yamaguchi began her skating career in pairs competition and won her first U.S. championship at the age of 15. She won her first singles competition at 17 and continued to compete and train while getting her psychology degree at the University of Alberta. She took gold at the Albertville, France, Olympic Games in 1992.

Entrepreneurial Ventures: Four years after her Olympic victory, Yamaguchi started the Always Dream Foundation to help fight childhood illiteracy. She then wrote the children's book Dream Big, Little Pig hitting The New York Times bestseller list and receiving the Gelett Burgess Children's Book Award. She also started a line of women's activewear in 2012.

Kahka Kaladze

Athletic Career: Like many top soccer players, he started his career playing for his local club as a teenager. He was 16 when he made his top-flight debut, and started his pro career with Milan at age 23. He played for Milan and Genoa while maintaining a solid core of fans in his home country of Georgia.

Entrepreneurial Ventures: Kaladze is the owner of Kala Capital, a company with investments in energy concerns in Georgia, Italy, Ukraine and Kazakhstan. He also owns restaurants in Kiev and Milan.

What's the most important lesson you've learned from playing sports? Join the conversation in the comments below.

Jason has contributed over 2,000 blog and magazine articles to publications local, regional and national. He speaks regularly at writing and business conferences. You can find out more about Jason at his website.

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