Jiang Bing, who suffers from rare Lou Gehrig's disease, also known as ALS, has achieved a miracle by surviving for more than 30 years.

As a token of his appreciation, he has been tutoring students for free for over two decades.

Jiang, a native of Weinan, Northwest China's Shaanxi province, fell to the ground on the way to school when he was 16 years old, a junior high school student, in 1985, and he was unable to stand up again.

A doctor in Chengdu, Sichuan province, told him that he had a strange disease that was hard to be cured, and suggested giving up searching for treatment. The doctor said he might not survive after 23.

Jiang at that time did not know anything about the disease, but his parents began taking care of him and started making his favorite meals.

"I was aware that I had a disease that could not be cured, and I thought I would live for a short time. I went to markets, parks and other places to feel and observe everything after having studying in the morning," Jiang said.

"I had no fear or despair at that time and cherished every moment, spending one day like a month, because I did not know when I might leave the world," he said.

He observed the horses and cattle sold at the markets, and painted them, and his paintings were showcased in competition in Japan and won a prize, he said.

In July 1988, Jiang participated in the national college entrance exams. He said his score above the required cutoff of Tongji University in Shanghai, but because he was unable to pass the physical tests he was not admitted.

After graduating from high school, Jiang worked as a community worker recording coal use of residents for a year, and then gave up work.

Jiang began tutoring his younger sister, and she secured admission in a university in 1994. Residents living in the community realized that he could teach their children and asked him for help.

"In 1995, I started helping children with their studies. Apart from the academic subjects, I also teach them fine arts and clay sculpture. I once taught 24 children in one single class, all for free," Jiang said.

"These children and their parents also help me, such as changing quilt covers and cleaning around. Though it's difficult to move around, I still like doing what I like and am satisfied with my life," he said.

Between 1995 and 2017, Jiang has helped more than 200 students. In early May 2005, Jiang completely lost the ability to walk and could only move on a wheelchair, but he continued to help students.

"Many have graduated from universities, with some working as actors, designers and directors. The design work of Deng Hua won the gold lion in Cannes contest," he said.

Zhao Feiyu, a student who received Jiang's help, said Jiang teaches them conscientiously and thoroughly, and he took no money in more than two years. "He is my teacher and friend," he said.

"After graduating from college I began running an art training school, hoping to help more students like Jiang," he said.

However, with Jiang and his parents getting old, he finally accepted advice from friends to receive payments for teaching children this year.

"I only receive 450 yuan ($67.6) subsistence allowance a month and have no other source of income. But I will continue to teach poor children for free," Jiang said.

An official from Weinan human resources and social security bureau said that Jiang could join in the social endowment insurance for urban and rural residents and medical insurance for urban residents, which will secure him for living allowance and medical funds.