Bad
frazzled - To feel completely exhausted and worn out, and unable to think straight, after a great deal of mental or physical effort
After being up two nights in a row writing a 60 page history paper, and drinking 60 cups of coffee, Simon's mind felt frazzled.
Expendable - Not essential, able to be used up or sacrificed without significant loss, easily replaced or not necessary for long-term use.

The workers didn't feel any sense of job security, and they felt expendable, because they were fired whenever the demand for the factory work slowed down.