If you train people properly, they won't be able to tell a drill from the real thing. If anything, the real thing will be easier.
Change hurts. It makes people insecure, confused, and angry. People want things to be the same as they've always been, because that makes life easier. But, if you're a leader, you can't let your people hang on to the past.
Popularity is not leadership.
Pain was their body's way of telling them that they'd pushed themselves to their limits -- which was exactly where they were supposed to be.
We all knew there was just one way to improve our odds for survival: train, train, train. Sometimes, if your training is properly intense it will kill you. More often -- much, much more often -- it will save your life.