Could the secret to success lay in taking cold showers? Some celebrities and CEOs swear by it, claiming that the frigid temps help to clear their minds. In a 2021 tweet, Dwayne “The Rock” Johnson revealed he takes a cold shower every morning to help jumpstart his day, as well as combat inflammation and boost his metabolism. And he’s not the only one.

For context, I don’t take freezing showers in the morning but it’s chilly and has a great “morning bite” to wake me up, clear cobwebs and get rollin’ with my day

Great for inflammation and metabolism too@HannahYasharoff https://t.co/nD0Iuo3iD0

— Dwayne Johnson (@TheRock) August 18, 2021

@HannahYasharoff

Billionaire Twitter founder and Square CEO, Jack Dorsey, not only wakes up at 5 a.m., he also starts his day with an ice-cold bath. WHOOP founder and CEO, Will Ahmed, told Fortune that cold showers and meditation are part of his morning routine. Meanwhile, Matteo Franceschetti, cofounder and CEO of Eight Sleep, swears by thermal shock as part of his nighttime routine—starting with a sauna or hot bath, followed by an ice bath or cold shower.

But what does science say? As it turns out, there are real physical and mental benefits to starting your day with a cold shower, which is defined as a shower with a water temperature below 70 degrees Fahrenheit.

Here are three reasons why you might want to incorporate a cold shower into your daily routine:

Improve your physical health

A study published in PLOS One showed that people who regularly took cold showers saw a 29% reduction in sickness-related absences from work—though it didn’t reduce the number of days a person was sick. Another study noted that cold showers contribute to the “improvement of the immune system, cardiovascular circulation and vitality,” although proven associations remain unclear. There is also data that suggests showers may decrease inflammation, increase longevity, and improve your metabolism.

Improve your mood

In a clinical trial, researchers found that taking a cold shower for up to five minutes once or twice daily can help relieve symptoms of depression. Cold showers can also help clear your mind and combat overwhelm by decreasing your heart rate. Short on time or already took your shower for the day? Splashing your face with cold water, taking a walk on a cold day, or holding an ice cube can also help, according to Dialectical Behavior Therapy, which is a type of psychotherapy especially designed for people who experience emotions intensely.

Increase your willpower

In Dr. Kelly McGonigal’s book, The Willpower Instinct, the health psychologist explains that doing uncomfortable activities, such as taking a cold shower, helps build willpower and the neural pathways that contribute to resilience.

Athlete Joel Runyon backs this theory up in his popular TED talk about “Cold Shower Therapy.”

“After you’ve stared at the shower head and conquered the cold in the shower that morning, you begin to recognize that hesitation,” he wrote in a blog post. “You realize the hesitation you have when it comes to the project/business/workout is the exact same fear you see in the shower. And you realize you’ve already beaten it once that day and that the only way it can actually hurt you is by stopping you from doing what you need to do.”

Getting started with cold showers

While cold water immersion is all the rage among athletes and influencers, such as the Dutch motivational speaker behind the popular Wim Hof Method, too much cold exposure can cause your blood pressure to drop.

If you want to give it a try experts recommend starting slow and small—by either gradually decreasing the temperature of your shower, or finishing your shower with a blast of cold water, as Dr. Dominic King, a sports medicine physician in the department of orthopaedic surgery at the Cleveland Clinic, previously told Fortune.

You can start by taking a cold five-minute shower and slowly work your way up to 10 minutes. It’s also best to take a cold shower in the morning to set yourself up for success for the remainder of the day.