Anything in life can get tiring. A soldier gets tired of fighting a war, a cop gets tired of police work, a doctor loses too many patients and gets worn out... You just have to weigh your priorities and find a way to either change things or get through it.
I have no idea what a Mynock is, but if I'm expected to feel bad about slaying some literally soulless killers that have murdered innocents or tried to end the world, that's not going to happen. There are plenty of things and choices in life to feel bad about, but I don't think that protecting innocent people are one of them.