Four minutes before a hard conversation, rehearsing it one more time makes it worse. You already know what you want to say. What is missing is the ability to say it slowly.

Counted breathing does one useful thing here: it occupies the part of your attention that would otherwise run the conversation in a loop. In for 4, hold for 4, out for 4, hold for 4. When you lose the count, start at 1 again. Losing the count is not a failure — it is the exercise.

Close the other tabs first. Not for tidiness: you want one thing on screen so there is nothing to flick to. Then let the breath out get longer for the last minute, and go in.

You will not be calm. You will be about one notch slower, which is usually the difference between the sentence you meant and the sentence you regret.