He had to climb steep mountain ladders, cross suspension bridges and thread his way through narrow and perilous trails.

"Some sections on the edge of the cliff required both hands and feet to get through," Du says.

"When it rained or snowed, I had to be more cautious about it becoming slippery," he adds.

Some road sections were practically vertical and were infamous for claiming lives.

To avoid the risks, villagers had to take a detour by bypassing several mountains to get to the outside.

Yet, Du had long overcome the fear through years of practice.

"I guess practice makes perfect," he says, half-jokingly.

The arduous return trips saw Du wear out more than 110 pairs of shoes and more than 3,000 crutches.

Based on his worksheets, Du had walked 130,000 km at work and his efforts have earned him the nickname "angel courier" among locals.

Traveling in the mountains, Du often encountered wild animals, such as boars, foxes and bears. He would adeptly take cover and dodge them.

"I just waited for them to leave before continuing to hit the road," he recalls.

The poor communication signals back then also caused concern for his family and they advised him to quit and find another job. But, Du had clearly developed a close bond with the local villagers and refused to give up on his challenging job.

Five days a week in the mountain made it a necessity for Du to stay over at villagers' homes for the nights.

"They were particularly enthusiastic and even fought for their turn to have me in," Du says.

"It is clear that they have come to treat me like their own family members."

He also got to know many villagers better through the interactions during his stay.

Du made a point of taking note of their requirements and tried his best to answer their prayers on his own.