It depends. If my plans change because of some unwanted external stimuli, it's bad, but if the plan(s) changes for the better, if something I've been waiting forward interferes (which is a rarity), it's not that bad and I can get over. I've found a way to remain in control in overwhelming situations, and that is to delay the 'explosion' of anger and anxiety using a timer. For example, if my daily routine is interrupted by my mother who wants to go and buy me a new pair of trousers, I mentally demand myself to remain in control for one more hour. If we're not back in one hour, then it's fine to lose it. And it works, though I'm agitated most of the time.