You should never be upset about the things that happen in the normal course of business. You should take these things seriously, and you should do your best to try to prevent the things that go wrong—especially if they are systemic. But when the things that are always going to go wrong do go wrong, being emotional isn’t of much use.
I learned this from flying. Your plane is going to be delayed. Your crew is going to show up late, and so will your pilots. You will have mechanicals that prevent you from being able to fly, and you are going to get stuck for hours. Fortunately, if I have a laptop and a video camera, I have work available, and I have the time to do it (even if the environment isn’t always what I would want it to be).
Your operations team is going to struggle to execute the solution you sold your dream client. They are going to miss deadlines, and your client is going to be unhappy—or worse. Sometimes it will be your team’s fault, and sometimes it will be your client that needs to make changes. Because it happens, there is no reason to respond emotionally, as that only makes it more difficult to make the changes you need to back to get things back on track.
The accounts receivable department is going to bill your new client incorrectly. For five weeks in a row. You are only going to be notified when your client has overpaid tens of thousands of dollars, and only when the problem is large enough to make them question your integrity. There is no reason to rip into anyone for making a mistake. The only thing for you to do is to make sure it is corrected, and ensure that if the problem is systemic, that someone does something to put a new process in place.
I promise you are going to have unreasonable clients, ones with unreasonable expectations who don’t pick up their end of the stick, and who are just difficult personalities. Almost none of their vitriol or hostility has anything to do with you. They didn’t sleep well. They are dehydrated. They have low blood sugar. They have an overdue bill they are having trouble paying. They have an elderly parent they are trying to take care of, and they are under stress taking care of their own family. All you can do is give them your very best effort to take care of them.
Take problems seriously, but not personally. These challenges don’t define you, even when you created the problem or challenge. How you respond is what defines you. Are you positive, empowered, optimistic, and future-oriented? Your job is to define yourself by possessing these attributes, and by doing your very best work.