You Don't Grow in Your Comfort Zone
By: Brian Hoeflinger, MD
May 3, 2026 | #85
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Disclaimer: Opinions are my own. Not medical advice.
Medical Trivia of the Week
Research suggests that during extreme endurance events, the sensation of fatigue originates primarily in which of the following? (the correct answer is at the end of this email)
- A) The cardiovascular system
- B) The muscles themselves
- C) The brain, via a central governor mechanism
- D) The adrenal glands
My Son and I Signed Up for a Half Ironman
I have a full-time job as a neurosurgeon. I am not a professional athlete. And I am not as young as I used to be.
So when I tell you that I just signed up to swim 1.2 miles, bike 56 miles, and then run a half marathon (13.1 miles) with my son, Kevin, in Michigan this September, I understand if your first reaction is to question my judgment.
But here is the thing. I did not sign up because it is easy. I signed up because it is not.
What Is an Ironman 70.3?
For those who are not familiar, an Ironman 70.3, also called a Half Ironman, is a triathlon that covers a total of 70.3 miles. It starts with a 1.2 mile open water swim, followed by a 56 mile bike leg, and finishes with a 13.1 mile run (half marathon distance). All three disciplines are completed one after the other, with no rest in between.
It is a very demanding single-day endurance event. The athletes who compete in these races are not all professional. Most are regular people with regular jobs who decided to do something hard on purpose.
Why We Do Hard Things
Ever since my son Brian died in 2013, Kevin and I have made a point of doing things Brian no longer has the opportunity to do. In 2024, we climbed Mount Kilimanjaro together. In 2025, we summited Mount Bierstadt, a 14,000-foot peak in Colorado. Not because we had to. Because we could, and he cannot. That is reason enough.
We also do it because we believe that most people are capable of far more than they give themselves credit for. The limits people accept are usually the ones they have never tested. If a neurosurgeon in his early 60s and his son can climb a mountain or race 70.3 miles, so can you. Maybe not this race, maybe not this mountain. But your version of it exists. You are more capable than you think. Go find out how much!
Your Brain Quits Before Your Body Does
Most people assume that when they hit a wall during exercise, it is because the muscles have run out of fuel or the heart can't keep up. That is not quite right.
Exercise scientists have a concept called the central governor theory. The idea is that the brain acts as a regulator during endurance effort. Long before your body actually reaches its true physical limit, the brain begins sending signals to slow down. You feel it as exhaustion, as the urge to stop, as the sense that you have nothing left.
But that feeling is not always accurate. It is the brain's best estimate of what it thinks you can handle, based on everything it is reading from the body at that moment. And like any estimate, it can be wrong.
Elite endurance athletes train themselves to recognize this signal and push past it. Not recklessly, but with the knowledge that the wall is often a checkpoint, not a finish line. The body has more capacity than the brain is willing to admit.
I think about this a lot. As a surgeon, I make high-stakes decisions under pressure. I know what it feels like to push through discomfort, fatigue, and uncertainty and keep performing. An Ironman 70.3 asks for the same thing, just in a different setting.
We Are Racing for More Than a Finish Line
Kevin and I are competing as part of Team IMF, the official charity team of the Ironman Foundation.
Since 2003, the Ironman Foundation has provided over 60 million dollars to nonprofit organizations in race communities around the world. These are local, regional, national, and global initiatives that create real, lasting change in the communities that host these events. The athletes who race on Team IMF are there because they believe the race means something beyond the medal.
We do too.
As part of our Team IMF commitment, Kevin and I have pledged to raise funds to support these initiatives. If this mission resonates with you and you would like to support us, we would be truly grateful.
Click here to visit our fundraising page.
Why I'm Telling You This
I share this with you not to impress you. I share it because I believe that one of the most important things any of us can do for our health, at any age, is to keep asking something hard of ourselves.
The research on longevity and brain health consistently points in the same direction. People who age well physically and mentally are the ones who keep moving, keep challenging themselves, and keep finding reasons to show up even when the comfortable choice is obvious.
You do not have to do a triathlon. But find your version of the hard thing. Sign up for it. Tell someone about it. Make it real.
I will keep you updated on the training as we go. And I hope somewhere in this, you feel a little nudge to do something uncomfortable.
It is worth it. I promise.
Impactful Quote of the Week
"It always seems impossible until it's done."
- Nelson Mandela
Please let me know what you thought of this newsletter by replying to this email.
All my best,
Brian Hoeflinger
P.S. - if you enjoyed this newsletter, you may enjoy my book that details my life as a neurosurgeon and the loss of my oldest son, Brian (see below a synopsis) and/or my podcast where I explain topics in further detail.
Learn More About My Book
Life and Death . . . Two words with such opposite meaning and which inflict such contradictory emotions and yet are so closely intertwined in our lives. As parents, we bring meaning and life into this world through our children. Our lives become defined as a result. We learn the joy, hardship, and responsibility of shaping an innocent life. But a day will come when that life will be taken. For some, death will come too soon. This is the story of my son, Brian Nicholas Hoeflinger, who died unexpectedly at age 18.
https://doctorhoeflinger.com/products/the-night-he-died-the-harsh-reality-of-teenage-drinking
Check Out My Free Podcast
The Dr. Hoeflinger Podcast is about more than medicine, it’s about living a fuller, healthier, and more meaningful life. My son, Kevin, and I discuss medicine, health, fitness, lessons learned from personal tragedy, family, and purpose. Along the way, we invite inspiring guests to bring fresh insights and perspectives. Watch or listen to the podcast below.
YouTube: Click here
Apple Podcasts: Click here
Spotify: Click here
Please reply with any questions you may have or future topics that you want me to write about.
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Medical Trivia Answer:
The correct answer is C) The brain, via a central governor mechanism
*Disclaimer: This newsletter and blog is for general informational purposes only and does not constitute the practice of medicine, nursing, or other professional health care services, including the giving of medical advice, and no doctor/patient relationship is formed. The use of information on this newsletter and blog or materials linked from this newsletter and blog is at the user’s own risk. The content of this newsletter and blog is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Users should not disregard or delay seeking medical advice for any medical condition they may have and should consult their healthcare professionals for any such conditions.
