Chen Jinliang often works 14 hours a day delivering items across Shanghai. [Photo by Gao Erqiang/Shanghai Star]

Working as a courier in Shanghai is tough work, Wu Ni chats to deliveryman Chen Jinliang about the realities of life on the road.

Dragging a large canvas sack filled with envelopes and boxes, Chen Jinliang rushes from one floor to another in office buildings near Nanjing road, handing out letters and parcels.

Chen is a courier with STO Express, one of China's major logistics companies. It is a job that keeps him on the run.

Being a courier is piecework, delivering a letter earns him 1 yuan (16 cents), while collecting a letter is 0.3 yuan, meaning that he rarely has time to pause. He rises at 6 am, sorts out all the packages by address and arrives at the office buildings before 9 am when most companies open their doors. He hands over about 250 packages a day, and collects more until 7 pm.

Chen comes from a village in Hanzhong, northwest China's Sha'anxi province. After graduating from high school at age 18, he got his first job as a courier with STO and has worked there ever since.

"I was ecstatic when I got my first salary. It was 1,200 yuan. All the hardship of work was gone. I finally can live on my own wage," the 25-year-old recalls.

Young, diligent and eager to trade their labor for more income, large numbers of migrant workers like Chen have formed the pillar of the fast-expanding courier industry. In 2014, parcels and boxes delivered in Shanghai, Beijing and Guangzhou all exceeded one billion, according to the State Post Bureau.

Most parcels contain items ordered with a click of mouse. Online shopping surges often before Spring Festival, Christmas and around Nov 11, or the Singles' Day, China's biggest online shopping event created by e-commerce giants Alibaba and JD.com.

"The double eleven (11.11) is really terrible," Chen says, his face still showing some awe when recalling the situation.