After his graduation, he didn't choose to go to more developed cities for better chances of work, but instead stayed in Lanzhou as a rescuer. "I read a book co-authored by late Harvard Business School teacher Clayton M.Christensen, titled How Will You Measure Your Life, in which he says, 'the only metrics that will truly matter to my life are the individuals whom I have been able to help, one by one, to become better people'. It inspired me and convinced me of the value of my work," says Yu.

During a rescue effort at the scene of an earthquake in 2013, a drone recording vital information of the affected area suddenly dropped out of the sky, landing on a cliff more than 40 meters high. To get it back, Yu had to cross a 10-meter-wide river and then climb the mountain.

As he reached the 10-meter mark of the climb, an aftershock hit. He paused and waited patiently for it to end, before continuing his ascent. Another aftershock occurred as Yu approached a height of 30 meters. "Many stones, similar to the size of eggs, rained down, hitting my helmet. At the time, I thought I was done for, and I was preparing for the worst," says Yu. After "a very long" five minutes, the aftershock subsided and he was able to finish the climb. After more than an hour, he finally reached and recovered the drone.

When asked if he has ever felt afraid in the course of his work, Yu says: "It would be a lie if I say that I have not, especially when I had just started the job, but I believe nothing is as important as saving lives. The urge to protect life is always stronger than fear."

Li Yun, a colleague of Yu, told China Media Group: "He is always tough in the face of a disaster. He is devoted to rescuing people, despite all the hardships he has endured. That makes me respect him very much."

Yu has also joined international rescue teams and was drafted in to help in the aftermath of a massive, devastating earthquake that hit Nepal in 2015. He was at the scene of a destructive flood in Myanmar that same year.

Yu believes that there are four stages to establishing an effective public welfare cause: Helping others directly, influencing more people to join, integrating resources and leading the development of the industry.

"The public welfare we usually see is still in the primitive stage, which is people helping others with good intentions. That is easy to accomplish, but, if you want to build an effective system, to establish an organization, that is another issue," says Yu.

"Saving lives is just the foundation. You also need to urge more people to learn about disaster awareness and mitigation, and then encourage them to participate in the process of rescuing and helping others. After that, you need to integrate the required resources effectively, and in this way, you can further the development of the emergency rescue field. That is what I want to achieve," he adds.