(I don't count to ten)
This applies for small things, but most things that people get distressed about are small.
Sometimes I even make an effort to think to myself, "How would X respond to this situation?" Replace "X" with anyone of your choice who would probably be a lot cooler than you under stress: Jesus, Spock, Batman, James Bond, Yoda, Mr. Rogers, or whoever the heck epitomizes "chill" in your worldview.
It sounds cheesy, and it probably is. But it works. Chances are, the "X" of your choice wouldn't react hastily or let small things get to him. Shit happens to everybody, but stopping in mid-emotional-flareup to process an appropriate response is a skill. And skills can be developed.
For example, when someone insults you in an offensive way. Why be annoyed? If it's true you should fix it; if it's false then he's mistaken. By remembering that, when I see that I'm about to become annoyed, my list reminds me to stay mellow.
"Don't let yourself be annoyed by minor things for very long" might be a more realistic take.