It was 1:30 in the morning and Chinese billionaire Chen Guangbiao wasn't able to fall asleep.

He had an important decision to make.

Rising from his bed, he sat and penned a letter, in which he promised to give his entire fortune to charity after he leaves the world.

It was, effectively, an acceptance letter to an invitation from fellow billionaires Bill Gates and Warren Buffett to attend a charity dinner on Sept 29 in Beijing, as well as a response to earlier pledges they made in the United States - agreed to by 38 other billionaires - to give, at least, half of their wealth to charity after their deaths.

The Sept 5 letter was later posted on his company website, bringing the 42-year-old billionaire into the media spotlight once again.

As early as 2007, Chen, chairman of a recycling company in Jiangsu province, announced that he would give away 95 percent of his property.

"Every year I will donate at least 50 percent of my company's profits to charity," Chen explained.

So far, Chen has donated more than 1.3 billion yuan ($192 million) and helped more than 700,000 people.

He claimed his current assets stand at about 5 billion yuan. "I will not keep any wealth for my children. I started from scratch and they can do the same," Chen said.

"They are very clever. Both are top students in their classes. Their excellence eases my worries."

Chen quoted his youngest son as having said: "My father is China's top philanthropist, but I will be the world's top philanthropist."

"They are just like me," the proud father added.

Chen's sister works in the kitchen of a restaurant in Nanjing, capital of Jiangsu province, for 1,800 yuan a month.

His younger brother earns almost as much.

He refuses to subsidize their living expenses, but fully supports their children's education. Chen leads a frugal life. He doesn't smoke or drink and eats in his company's staff canteen most of the time.

"A person who has been through a severe winter knows how precious sunshine is," Chen said.

Born into a farmer's family, Chen spent his childhood in poverty.

Two of his siblings died from malnutrition.

Since the age of 10, Chen earned his own tuition to continue his studies.

As many rural areas in China did not have tap water in the 1970s, he used to carry water to the local market 2 kms away, which he sold to passers-by. He earned 4 yuan throughout the summer, with which he not only paid his own tuition for that year, but also helped one of his classmates.

"That was my first donation and my teacher awarded me a red paper flower for it in class," Chen recalled.

"The honor and the feeling of giving made me so happy, which encouraged me to continue to help others."

As a result of his earlier experience, he trained himself to become an entrepreneur by the time he made his way to college, where he majored in traditional Chinese medicine.

His fortune began to accumulate from selling medical equipment in 1998.

He gave 30,000 yuan of it to Zhu Lili, age 13, who suffered from heart disease and had no money for treatment.

The girl has since grown up healthily and graduated from college.

Zhu was one of the thousands of people whose lives have been changed thanks to Chen.

Half of Chen's donations have gone directly to recipients, whom Chen personally met in remote, poverty-stricken or disaster-hit areas.

"Over the last two years, I've occasionally brought my sons with me to those places," he said.

"It's necessary for them to see the real need, sorrow and love."

The Bill & Melinda Gates Foundation invited about 50 of China's super-rich to the dinner.

But only Chen and Zhang Xin, CEO of real estate developer SOHO China, have publicly confirmed their attendance.

"Many entrepreneurs don't want to expose their wealth to the public, because some of it may come from gray income and they are worried about being investigated by the taxation bureau," Chen said.

"They are also concerned about the non-transparency of many charity organizations and not knowing where their donations end up."

Chen admitted he shared some of their concerns, but was more disappointed by their indifferent attitude towards philanthropy.

He has always encouraged his rich friends to donate. "I want to spearhead a change in values and facilitate the development of philanthropy in China," Chen said. "By donating my entire fortune to charity, I'm putting pressure on other rich Chinese. Hopefully, they will follow."