Why does my heart race and my hands shake after dealing with an angry customer?
Your heart races and your hands shake because your brain has treated the angry customer as a physical threat and flooded your body with adrenaline — the fight/flight response. Your heart speeds up to move oxygen fast, your breathing quickens, your pupils dilate, your digestion shuts down (that churning stomach), and you may go red and sweat. None of this means you are weak or bad at your job. It means your survival system fired exactly as designed. And here is the important part: humans can train themselves to respond differently. The reaction is natural. Staying at its mercy is optional.
Most people misread the shaking as evidence about themselves — "I can't handle confrontation." Wrong lesson. The shaking is chemistry, not character. What separates people who thrive under fire from people who dread it is not calmer biology. It's training.
What's happening in your brain
In my book Thriving Under Fire, I explain it through the three major parts of the brain:
The reptilian brain keeps your body running — heartbeat, breathing, digestion. It just happens; you mostly can't regulate it.
The mammalian brain (the limbic system) is concerned with survival. It's tuned for threat. When it detects one — a barking dog, a sudden bang, or a customer shouting across the counter — it signals your adrenal glands to pump adrenaline so you can react fast. Fight, or flight.
The neo cortex is the newest part: your thinking brain. This is where humans differ from other animals. We can work out alternative ways to think, feel, and act when the mammalian brain is screaming fight-or-run.
Your body can't tell the difference between a snarling dog and a snarling customer. The alarm is the same. The adrenaline is the same. The shaking afterwards is the same — it's the chemistry draining out.
The reaction is trainable
If we were exactly like other animals, that would be the end of the story. We're not. Even animals can be trained past their instincts — guide dogs learn to stay steady through noise and chaos that would send any untrained dog running. Humans, with a fully developed thinking brain, can go much further.
This is exactly where the APE Principle does its work. The training, in practice:
Breathe deeply, from the belly. Adrenaline makes your breathing fast and shallow; deliberate slow breathing tells the alarm system the threat is passing.
Name what you're feeling, silently. "I'm rattled." "That frightened me." Naming re-engages the thinking brain. To name them is to tame them.
Reframe the threat. This person is not a predator. They're a customer with a problem, expressing it badly. Your body stands down faster when your thinking brain re-labels the situation.
Respond to their emotion. "This has really upset you, hasn't it." Now you're working the situation instead of surviving it.
Afterwards, let the adrenaline drain. Shaking hands after the event are normal. Breathe, move, tell a colleague what happened. Two minutes of debrief stops it following you home.
Each time you do this, the training deepens. It takes real commitment — I won't pretend otherwise. But thousands of the frontline staff and managers I've trained since 1999 started exactly where you are: shaking hands, racing heart, dreading the next one.
FAQ
Is it normal to shake after a confrontation at work? Completely. Shaking is adrenaline leaving your system after the threat passes. It says nothing about your competence or courage.
Why does my stomach churn when a customer starts yelling? Adrenaline shuts down digestion so blood can go where fight-or-flight needs it. The churning or tightening is that process — uncomfortable, harmless, and temporary.
How do I calm down quickly in the middle of the moment? Slow belly breathing plus silently naming your feeling. Those two moves re-engage your thinking brain within seconds. Feeling your feet on the floor helps some people anchor as well.
Can I actually train away my fear response, or just hide it better? Genuinely train it. The alarm may still ring, but with practice it rings quieter and you recover faster. This is skills training, not acting.
Why do I keep replaying the confrontation hours later? Your mind is trying to finish an unfinished threat. Debriefing with a colleague, naming what you felt, and knowing what you'd do next time all help close the file.
Does caffeine make this worse? Caffeine raises your baseline arousal, so a system already primed by a stressful shift will fire harder. On heavy days, it's worth noticing the connection. [VERIFY — general knowledge, not from TUF source material; cut if you prefer]
Key takeaways
Racing heart, quick breath, churning stomach: that's adrenaline doing its job.
Your body can't tell a snarling customer from a snarling dog. The alarm is identical.
The reaction is chemistry, not character.
Your thinking brain can be trained to override the alarm — breathe, name the feeling, reframe.
Shaking afterwards is the adrenaline draining. Debrief for two minutes so it doesn't follow you home.
Find where conflict is quietly costing you
Have the first words ready before the next alarm goes off. Download the Emotion Acknowledgement Phrase Sheet. [LINK TO PHRASE SHEET]
This post links up to the pillar: What is the APE Principle?
John Faisandier is the founder of TUF: Thriving Under Fire and creator of the APE Principle. Since 1999 he has trained thousands of managers and frontline staff across New Zealand and Australia to handle emotionally charged situations at work. He is the author of "Thriving Under Fire: turn difficult customers into business success" and runs the Conflict Free Leadership program for managers.
