I was being transported to a hospital for a medical procedure, and I was talking to the guard who taking me, to pass the time. I asked him why on earth he would want to be a prison guard -- after all, they are in there with us for 10 hour shifts, and prisons are some of the most bleak/depressing places on earth. That has to take a toll on their mental wellbeing too.
He said that he originally was a regular police officer, but after seeing how much corruption there was in the police force and the things that happened, he felt like a hypocrite, so he said the better alternative was for him to be a guard.
That conversation has stuck with me for a long time now.