it's discipline, not habit. it's part of boot camp- you just can't do the job without it. the younger ones will follow the example of the seasoned guys. the more seasoned they are the less likely they'll be to do heinous shit. there was an old story going around the 2a boards. it was about an army officer who was doing some sort of survey for a college course, asking the troops if they'd fire on American citizens. the newer they were the more likely they would just do it. less likely the further up they got until they hit the spec forces types and hardly any would do it.