In The Metamorphosis, how does Gregor feel about his job and how do you know?

At the beginning of
, Gregor explicitly mentions that he detests his job as a traveling
salesman. He says:

"There's the curse of traveling,
worries about making train connections, bad and irregular food, contact with different people
all the time so that you can never get to know anyone or become friendly with them. It can all
go to Hell!"

He goes on to say that he hates getting
up early and that he never gets sufficient sleep. He stays at his job, however, because his
parents' owe his boss money, and he needs to protect his parents and his sister. He thinks that
in five or six years, he will quit his job, once he's paid off the debt. 

Although he has already turned into a "horrible vermin," Gregor attempts to get out of
his bed because he's afraid of being late to work. As he struggles to get out of bed, the chief
clerk from his office comes around to his parents' house to check why Gregor did not get on the
train as he was supposed to. The narrator says,"Why did Gregor...