Change. It's something that supposedly none of us like, but it's also inevitable. It's necessary for life to progress and exist, and according to Sheryl Crow, it'll do you good.
But no matter what the songs say and no matter how necessary it is, change can be difficult to deal with if for no other reason than it is what it is.
By definition, change means to "make different" or "cause a transformation" (and if you ask me, the definition should say something about how a single change is impossible because when one thing changes, so do about a million others).