The world's richest self-made woman shares her No. 1 key to success

Chinese billionaire Zhou Qunfei is the world's richest self-made woman, according to Forbes, and she attributes her success to one thing: perseverance.

Zhou, the 48-year-old CEO of Lens Technology, has built an empire manufacturing glass for tech giants such as Tesla, Apple and Samsung, but it hasn't been an easy ride to the top.

"I have encountered many difficulties and setbacks as an entrepreneur," she tells CNBC Make It. "If I gave up then, there wouldn't have been Zhou Qunfei or Lens Technology."

The hardship started early. Zhou's father, a skilled craftsman, went blind and lost a finger in a factory accident before she was born, and her mother died when she was 5. "I had to constantly think about where my next meal is and how I am going to get it," she says.

In 1986, at age 16, Zhou dropped out of high school to work as an assembly worker in a watch lens factory. She took accounting classes at night and dreamed of starting her own business.

By 1993, she'd saved 20,000 HK dollars (or about $2,500) to set up her first company — a family watch lens workshop. She and her seven cousins and siblings worked and lived together in a three-bedroom apartment for four years.

Over the next decade, Zhou built a factory making watch lenses and employed 1,000 people. But her darkest moment came in 2003 after she beat out competitors and won a contract with Motorola.

"A business rival was jealous," Zhou says. "That company teamed up with the raw material supplier and tried to squeeze me out of the game." The supplier defied industry norms and demanded full payment before delivering any materials.

Zhou sold her house and other valuables to meet the supplier's demands, but it still wasn't enough.

"I was desperate," she says. "I stood on the platform at Hung Hom Station in Hong Kong, almost jumped off, delirious, thinking that when I am gone, all the trouble will too be gone."

But then a phone call from her daughter pulled her back to reality. "I realized that for my family and employees, I cannot give up. I had to carry on." She sent a "911" email to Motorola, and with their help, she overcame the crisis.

In March 2015, Zhou's Lens Technology went public, and today the company is valued at $11.4 billion and has over 82,000 employees across China, according to Forbes.

"Many people would experience a serious blow to [their] confidence when they encountered setbacks," Zhou says, "but the key to success is to persevere, especially during the most difficult times."

People in the industry call Zhou by the nickname "Brother Fei" because they say she is as tough as a man. Some might say she's tougher.

When she took 20 executives on a team-building exercise to climb China's Dawei Mountain, which is more than 5,000 feet above sea level, some wanted to give up halfway up the hill. However, Zhou insisted that they not stop and march on.

"Because when you give up halfway, you won't have the courage to come back and start from the bottom all over again," she says. "Only when we persist, can we succeed. Don't give up because of a little setback."

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