Shenzhen, China (CNN) -- In a brightly-lit Shenzhen restaurant, 21-year-old Zheng Liqiang, a migrant worker from the inland province of Sichuan, describes his life in this southern Chinese city as "bu kai xin" -- glum. He says his working hours are too long; his salary too low and he has no personal life. "I feel lonely in this big city," he says. For the past three years, Zheng has been fixing photocopy machines at various factories in China's manufacturing heartland. His monthly salary of 3,500 to 4,500 yuan ($580 -$740) -- depending on overtime -- is higher than the average wage, but only because his job requires more risks -- the ink has toxic fumes.
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China has more than 260 million migrant workers
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Survey suggests many may suffer from mental health problems
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Leaving behind children and elderly parents an emotional and financial burden
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Better-educated and internet savvy, younger migrants suffer more than their elders
For young @placeholder and millions like him, the struggle is likely to continue.