One of the hardest work in Hanoi is the coal seller. You can see heaps of them riding around streets on a very simple bicycle without hand brakes full of coals about 2 meters high. Their clothes and bodies are black but their teeth are white. People joke that, if the coal sellers walk on a dark night without smiling, someone might get shocked to death when the black ghost appears.
These people ride hundreds of kms around Hanoi hunting for money, but according to one coal seller i spoke to, most of them seem accept the job despite the conditions