With over 9,500 locations, Curves International is the fastest growing fitness franchise in the world. The health club's all-female clientele and trademark 30-minute workout have generated astounding membership growth in little over a decade. Since founder Gary Heavin opened the gym in 1992, Curves has gained 80 percent of the women's fitness market within the overall $13 billion fitness-club industry.

Success didn't come easy for Curves founder Gary Heavin. The pre-med dropout launched a conventional fitness chain during his twenties, became a millionaire by age 30, and soon thereafter declared bankruptcy when his gym business imploded. Undaunted, Heavin went on to launch Curves International.

Today the Curves concept is expanding to new opportunities, from Curves-branded diet programs to travel services designed for club members. Tying together these diverse initiatives is one simple proposition: Curves is the place women go to "borrow willpower from a friend."