Margaret kept a rubber band on her wrist. Every time she felt her chest tighten before a work meeting, she'd snap it. It didn't help much. What she didn't know was that her body had two built-in tools far more powerful than any rubber band —and they'd been waiting for her to use them all along.

Those tools are your nervous system's two main divisions: the sympathetic system and the parasympathetic system. Together, they run almost everything you feel in your body—your heart rate, your breathing, your digestion, and even how well you sleep. Most of us have heard the phrase "fight or flight," but fewer people know that the other half of the equation—the recovery side—is just as important. And the good news? You have more control over both of these systems than you think.

You've probably heard some of what I'm about to outline before, but I don't think you've ever been told why some of it works or what biology is involved. You've been advised to use one system, while the other has been neglected. Today, let's talk about both of them.

The Gas Pedal and the Brake

Think of it this way. Your sympathetic nervous system (speed up or "pedal to the metal") is the gas pedal. It kicks in when you need to move fast, focus hard, or respond to a threat. Back when humans were running from predators, this was a lifesaver. Now it fires when you're stuck in traffic, arguing with someone you love, or scrolling through bad news at midnight.

When your gas pedal kicks in, your heart speeds up, your muscles tense, and your breathing gets shallow. Your body is ready for action. That's fine in the short term. But if the gas pedal stays stuck down—if you're running on stress hormones day after day—your body pays a price. You feel exhausted but can't sleep. You're irritable. Your stomach's upset. Your immune system isn't doing its best work. The sum total is that you are damaging your physical and mental health.

Your parasympathetic system is the brake. It slows things down. It tells your heart to slow down, your digestion to return to normal, and your mind to stop racing. It's the system that kicks in when you sit down to a good meal, take a slow walk, or breathe deeply and let your shoulders drop. Scientists sometimes call it the "rest and digest" system—and that name fits perfectly.

Here's what most people don't know: you can deliberately activate both of these systems. You don't have to wait for them to happen to you. How many of us have ever been trained to control these systems? I would say none of us.

Working with Your Gas Pedal

Your sympathetic system isn't the enemy. It's actually a gift when you use it right. Physical exercise is one of the best ways to put it to good use. When you exercise, you're telling your body, "Yes, burn that energy. There's a reason for it." And when the workout ends, your body gets a stronger signal to recover—which actually trains your parasympathetic system to kick in more efficiently over time.

That means regular movement, even a 20-minute brisk walk, doesn't just help your heart. It makes your whole nervous system more flexible. You get better at going from "on" to "off." You sleep better. You handle stress more easily. The gas pedal and the brake both get tuned up.

Cold water is another tool worth knowing about. Ending your shower with 30 seconds of cool water isn't torture—it's a signal to your sympathetic system to wake up and do its job. Research on cold exposure shows it can sharpen focus and lift mood, partly by triggering a controlled sympathetic response that your body then works to balance. You don't have to plunge into an ice bath. Just a few seconds of cooler water at the end of your shower can start to make a difference.

While I'm at it, let me put in a plug for muscles and what they do beyond helping us move. Research has shown that muscles function as glands and trigger a range of neurochemicals that affect the body through interconnected systems. It's still too complex to fully understand at this stage of the research. So, every time you use a muscle, you are doing more than moving, and it is incredibly creative. I've covered much of this in my latest book, "Get Out: A Shrink's Guide to Using the Great Outdoors as Therapy."

Working with Your Brake

The parasympathetic system (the pause system) is where most of us need the most help. We've gotten very good at stepping on the gas. Letting up on it? That's harder.

Breathing is probably your most powerful tool here—and it's free, it's always with you, and it works fast. When you slow your breathing down to about five or six breaths per minute—much slower than most people breathe—you activate something called the vagus nerve. The vagus nerve is like a superhighway between your brain and your body, and when it's humming along, your heart rate steadies, your blood pressure drops, and your mind calms.

You don't need to count precisely. Just breathe in for about four seconds, then out for six seconds. The longer the exhale is, the more it engages the brake. Do these exercises for two or three minutes and notice what changes. Some people do it sitting in the car before they walk into work. Some do it in bed when they can't fall asleep. It doesn't matter where. It matters that you do it.

Know what else works and you don't even give it much thought? Five minutes in the sunshine in the morning. All you have to do is stand there and let the sunshine envelop you for simply five minutes. No longer than that.

Humming and singing work for similar reasons. They activate the same vagal pathways as slow breathing. So does gargling. It might sound strange, but a few seconds of gargling water a day is an easy, low-tech way to tone up your parasympathetic system. Your vagus nerve runs through your throat—when you gargle, you're literally giving it a workout.

Touch matters more than most people realize. A warm bath, a massage, even a slow self-massage of your hands and forearms can shift your body out of high alert. And if you have a pet, you already know that stroking an animal lowers your heart rate. That's your brake working in real time.

Social connection is another powerful activator of the parasympathetic system. A real conversation—not a text exchange, but an actual face-to-face talk with someone you feel safe with—does something measurable to your nervous system. It signals safety. Your body picks up on the tone of voice, the facial expressions, the shared laughter. All of that tells your brain that you don't need to stay on guard.

Birds maintain this social connection through the calls they use. When they are calling, not on alert but just calling, it's reassuring that it's safe. I hear them all the time in my area, and I know when they're calling, it's fine, and when they're quiet, the hawk is coming around.

The Balance Is What Matters

Neither system is meant to run alone. You need both. The problem most people have today is that they're stuck on the gas pedal with a brake that doesn't engage reliably. Chronic stress does that. So does poor sleep, too much screen time, and not enough time outdoors or with people who make you feel safe.

The goal isn't to be permanently calm. It's about being flexible—to be able to shift between alert and at ease, to respond to what life throws at you, and then come back to center. Scientists call this capacity "autonomic flexibility," and it shows up in a measure called heart rate variability (HRV). People with higher HRV tend to be healthier, more emotionally resilient, and better at handling stress.

The good news is that all the things we've discussed—exercise, slow breathing, cold water exposure, humming, touch, and real human connection—have been shown to improve heart rate variability over time. They literally train your nervous system to be more responsive.

You already have two servants waiting to work for you. You don't need a rubber band. You just need to know how to give them the right signals. Start small. Pick one thing from this article—a slower exhale, a cooler rinse at the end of your shower, a five-minute walk—and try it for a week. See what happens. Your nervous system is far more responsive than you've been led to believe. Margaret eventually figured that out, too. She ditched the rubber band.