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.
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.