By the side of a busy road in Shanghai's financial district, Zhao Ping Hua is mixing cement.
By Quentin Sommerville
BBC News, Shanghai
Zhao Ping Hua describes a sacrifice worth paying for his children's future
Twenty years of a booming China have meant 20 years of back-breaking work for him.
He is a labourer on the city's new metro system, and one of the millions of farmers who leave the countryside every year for the riches of the city.
The wages are good here, as much as $250 (170 euros; £119) a month, with overtime.
But for him it means sacrifice, living away from his family, and he misses his children.
"I work really hard, for the wages I earn, to improve my family's life," he says.
"I tell my children to study hard, to improve their lives. Don't be like their Dad - a migrant labourer, working away from home. It's not a good life."
But he says has no choice. In Shanghai's building boom, he can earn four times as much as he would back in the countryside.
His is a journey that tens of millions of workers make every year, leaving their villages and their families behind.
China says there are as many as 20 million migrant workers, but unofficial estimates put the figure far higher.
It is a drive of about six hours to get to Zhao Ping Hua's village in Jiangsu province, to the north of Shanghai.
In a country the size of China that is not very far. But for Mr Zhao and his family, distance is not the issue.
Every penny counts, so he can only get home to see his wife and daughter once or maybe twice a year.
His wife Guo Xiumei is a housewife. She does a little farming on the side, growing rice, in the fields behind their simple home.
She will not see her husband for many months to come, he only makes it back during China's national holidays. It's her job to bring up their two children.
Despite the hardships, she has no complaints.
Migrant workers commonly live in communal accommodation
"Our children need to get a proper education - that's our priority. It doesn't matter if life is difficult for us, we want the best education for them. It's their only hope of a better life," she says.
Their son is at boarding school, but their daughter, Zhao Hui, has lessons at a school just round the corner.
She is a shy 13-year-old, but she already knows that she wants a different life to that of her parents.
"I miss my Dad very much - I'm so happy when he comes back.
"I want to be with him when I grow up. Some day I'll take care of him," she says.
Despite her father's hard work, the family lead a modest life. Most of the money is spent on school fees.
"We have more money now, but everything is more expensive - rice, pork, it all costs more.
"And we have to pay extra for good schools," Guo Xiumei adds.
Back in Shanghai, Zhao Ping Hua's day is ending.
He lives in a communal dorm with other workers. The thin metal walls means it is freezing during the winter nights, but he stays awake late, writing his diary.
He knows that there is nothing unusual about parents going without for their children's benefit.
But, as he writes in his diary, here in China, the sacrifice is far greater and the struggle is much harder.
For Mr Zhao and his wife, 20 years of living apart is a price worth paying, if their children do not have to do the same.