Right at the edge
Buy one beat and drop your volume.
You don't have to fix the situation in this second. You have to not pour fuel on it. Say out loud that you need a moment, then make your next sentence quieter and slower than the last one. Volume down tends to bring everything else down with it.
Try: "I need a second." Then one long exhale before you say anything else.
You caught it early
Good. That noticing is the skill.
If you can feel the jaw and the heat, you are ahead of where most people are, which is already mid-yell. Unclench your jaw, let your shoulders drop, and make your out-breath longer than your in-breath. A slower exhale is one of the few quick ways to nudge your own body off the gas.
Try: a slow breath out, shoulders down, hands unclenched, before you respond.
An old thread, not the child
This one is usually about you, and that's okay.
Feeling defied or disrespected can hit hard, because it touches your own history and your sense of authority. But a young child saying no is doing their developmental job, not staging a coup. Naming it to yourself takes some of the charge out: this is my trigger, not their crime.
Try internally: "They're not trying to disrespect me. I can hold the limit without the heat."
The clock is the trigger
Lower the demand before you raise your voice.
The 7:45am shoe standoff is rarely about the shoes. It's the deadline pressing on you. You can't add minutes, but you can cut the task: do it for them, drop a step, carry the shoes to the car. Getting there a little late and a little connected usually beats getting there on time and blown up.
Try: "I'm going to help your body get to the car. We'll finish the shoes there."
Running on empty
Lower the bar for today, on purpose.
On no sleep, your reserves are gone before the day starts. This is not the day to teach the big lesson or win the standoff. Aim for safe and connected, keep the demands small, and let some things slide that you'd normally hold. Doing less today isn't giving up. It's parenting from the floor you actually have.
Try: pick the one limit that truly matters right now, and let the rest be easy.
It already happened
Now the move is repair, not shame.
You yelled, or you got too harsh, and now you feel awful. That feeling means you care; it doesn't mean you broke anything that can't be mended. Once your own body settles, come back, name your part briefly, and reconnect. Repair is what protects the relationship, and your child learns from watching you do it.
See the repair tool for the words. Short is better than perfect.