A 74-year-old man named Yang Licheng from China's Zhejiang province has won a great deal of gratitude by repairing more than 4,000 public bicycles over the past three years, local media reported. 

Three years ago, Yang discovered that some of the bicycles provided by the local government did not work, but there was a long wait to have the bikes repaired. That delay significantly reduced the efficiency of the public bicycle system.

Given his experience fixing mechanical components, the kind-hearted man soon started volunteering his services. Later, in 2013, an alliance for volunteers wanting to repair the bicycles was initiated. Yang joined, first working at a station near his home, then eventually expanding his service area to over 20 other stations.

According to Yang, he spends at least two to three hours each day repairing bicycles. He has sometimes repaired more than 40 bicycles in a single day. Yang says that even though others view the task as tiring and dirty, he enjoys it as physical exercise. It also happens to help the public, he added.