Really knowing, understanding and accepting the concepts and possible outcomes goes a long way.
If you understand and accept that heads-up your aces will lose about 20% of the time, you don't go on a rant about bad beats when they get cracked. You will make a different decision, maybe to just accept it, or perhaps putting in more volume to level out the variance.
If someone at the table is obnoxious, I'm not going to let it affect my game. If Drunk and Rude Guy is at my table, that's good for me. Other players might tilt or lose concentration, but I won't, which gives me an edge. If he says my wife is a whore, I know that my job isn't to defend my family's honor. My job is to bring home money and make my wife happy.
I enter a poker room understanding what might go wrong, including getting knocked out by an 18-year-old playing his first tournament, which happened to me two months ago. I just told his mother, who was at the table and had bought her son into the tournament, that he should skip college and turn pro. She was shocked but the table got the joke. Then she laughed along with them.
Know what you're doing and why. Do the work. Put it the volume. Understand that over a small sample size a lot of things can go wrong, accept it and move on.