"’Course you get goddamn good an’ sick a-doin’ the same thing day after day for four years. If you done somepin you was ashamed of, you might think about that. But, hell, if I seen Herb Turnbull comin’ for me with a knife right now, I’d squash him down with a shovel again."
– John Steinbeck
The Grapes of Wrath, Chapter 6. Tom Joan talking to Muley Graves. Tom feels no guilt or regrets about killing Herb Turnbull, despite serving four years in prison for it. He would do the same thing again, if faced with the same situation.