I'm a tech exec who starts every day with a 3-minute cold plunge. My mind has never been sharper.

• Brad Margist is the chief technology officer of eVolve Computing and a cofounder of CyberHoot.
• He learned about the benefits of cold plunging and built his own for $600 out of a chest freezer.

This as-told-to essay is based on a conversation with Brad Margist, the 31-year-old chief technology officer of the software company eVolve Computing and a cofounder of the security-awareness and -training platform CyberHoot who lives in Charlotte, North Carolina, about his daily cold-plunge routine. It's been edited for length and clarity.

I'm one of those people who starts each day with a cold plunge for productivity and stress reduction.

I wake up at 7:30 a.m., make the bed, brush my teeth, put on a bathing suit or shorts, start the coffee pot, and grab a towel. At 8 — rain or shine, summer or winter — I walk out the back door to get into a chest freezer that I converted into a cold plunge for three minutes. I keep it on the side of my house on a pallet under a covering.

The freezer is plugged into a temperature-controlled outlet that powers it on and off to keep it in a set temperature range of 34 to 38 degrees Fahrenheit, which is an uncomfortable but safe temperature for me, as recommended by Andrew Huberman, a neuroscientist.

The biggest benefit I've seen after doing this regularly has been my mental shift. My morning cold plunge is usually the most challenging part of my day, so everything after that is much easier.

I began my cold-exposure journey in 2018

I started with cold showers after stumbling upon Wim Hof, also known as The Iceman. I heard about the concept on a podcast, did some research on the benefits, and was inspired to give cold showers a try.

I started out doing 30 seconds under the cold water for two weeks, then one minute for two weeks, then two minutes for two weeks. I worked my up to three minutes. I also would take a weekly three-minute ice bath in my bathtub by buying bags of ice and filling my tub with a mixture of water and ice.

The challenge with cold showers was the water would often not be as cold as I wanted it to be. It was also a lot of work to buy ice, bring it home, and fill the tub.

I decided to convert a chest freezer into a full cold plunge

What sparked the chest-freezer conversion was seeing examples online while researching cold-plunge options. Cold plunging has become a popular trend recently and there are many kinds available, but many cost over $10,000. I opted to save money by going the homemade route and converting a chest freezer myself as a fun DIY project.

I purchased a 14.8-cubic-foot chest freezer on OfferUp for $100 and followed a guide I found online, with a few modifications, to convert it into a cold plunge. I also later sealed the inside with bright blue Pond Shield, which was the most challenging part because it dries quickly, to prevent rust and add color to the inside of the freezer.

The total cost was around $600 for everything, and the entire conversion process took about one week. I also asked my fiancée to paint a yeti on the freezer lid to give it some style. She supports me in my cold plunging, but she's made it clear that it's not for her.

The first 30 seconds in the cold plunge are the hardest

At the start of the three minutes, I feel the shock of the cold before my body adapts. A sharp feeling of discomfort hits me, and my body wants to tense up and jump back out, but this painful period builds my mental fortitude. After the first 30 seconds, it becomes easier, and the relief of knowing the hard part is over kicks in.

The first 30 seconds is also when controlled breathing is the most important — and most difficult. I practice box breathing — a technique I learned from Ben Greenfield where I breathe in, hold my breath, breathe out, and hold my breath again — each for four seconds. This technique helps me maintain calm and consistent breathing and acts as a form of meditation.

When the three minutes are up, I dunk my head under the water and sometimes let out an audible "WOOOO!" as I climb out before I dry off.

When I get out, I have coffee, which I look forward to after being in the cold, but the cold plunge alone is enough to wake me up. I joke with myself that I must "earn" my cup of coffee each morning with a cold plunge beforehand — it makes that cup even more enjoyable.

After I've had my coffee fix, I'll feed my two cats and dog and do some reading, stretching, and meditating, or take a walk to relax before starting the workday at 9 a.m. I work from home every day, besides the occasional work trip every few months to meet with customers.

My goal in the beginning was to do this to help me wake up in the morning

I'm not a morning person. The first 30 minutes of my workday used to be full of yawning, eye rubbing, and a lack of focus. Now when I sit down at my desk after my cold plunge, I'm wide awake, focused, and ready to dive into deep work.

When I climb into the plunge, I'm still half asleep, and when I climb out, I'm amped to get the day started. Every now and again, if I have the time, I'll even jump in the cold plunge in the afternoon if I start having the feeling of midday grogginess.

Cold plunging has helped me manage my fight-or-flight response in stressful work or life situations

I find myself feeling less emotional during tough conversations after taking a cold plunge. When something frustrating happens, instead of going with my gut emotional reaction, I can instead pause and calmly respond to the situation.

Cold plunging has also reduced my stress by allowing me to better focus on the present without anxiety creeping in.

One day I had an important customer reach out and ask to chat. The request was unexpected, and I could've let the stress of wondering what the meeting could be about creep in. Instead, I was able to take a deep breath, acknowledge the stressful feeling, and then let it go and focus on the present. The customer meeting was actually very positive.

There are also many health benefits

I've experienced decreased inflammation and improved muscle recovery and immune support.

I'm an active person — I run, rock climb, and do strength training. I notice less muscle soreness with regular cold plunges. I've also noticed that I hardly ever get sick. I used to get a winter cold each year, but that has ceased as far as I can remember. My overall mood is more positive as well.