Ask Stew: How do I use fitness to build better basic immunity?



If the COVID-19 pandemic taught us anything, it is that good health comes with a strong immune system. Focusing on health and wellbeing is a matter of life and death. But for many, especially in the tactical profession, human performance is equally crucial.

Someday, your fitness and tactical skills will be determining factors in a potential life-or-death situation – either your own, that of your friend, or a victim you wish to help. That’s how important it is to take health, wellness, and fitness seriously.

Here is an email from a 35 year old man who plans to serve in the Army with a few other issues than the normal 18 year old recruit.


My name is Jim and I’ve worked hard in construction my whole life and always wanted to serve. I decided in 2022 to register at the age of 35. I would have signed up a few years ago, but with COVID, I figured I should wait out the locks and quarantines and work on my immune system.

I was always fit with my job and training for ranger school one day, but got sick every few months during allergy, cold, and flu seasons. Do you have any tips on how to stay fit and able to fight off colds (and less common illnesses) as you age? Just curious about your advice on how to balance exercise, work, diet and recreation as I see you write about it a lot. Thanks for your time, Jim.

Jim – great question, and thank you for considering serving in the military.

You’re right. Immune system health is something we all need to improve on as we have taken it for granted for most of our lives. However, seasonal illnesses, as well as common viruses and bacterial infections, are warning signs that should be addressed. I recently wrote an article about improving your immune system and you should take a look at that first and consider:

Why are you getting sick? Stress is our most important damaging factor in our ability to fight colds and illnesses. In your case, a huge stressor is training hard to prepare a body over 30 for ranger school. Add in a long day of work on a construction site, quick meals, alcohol consumption, and poor sleep and you have a recipe for overstress and under recovery that make you more susceptible to illness. If you burn that many calories a day and don’t eat enough to make up for that workload, your body fat percentage will drop. If your body fat percentage is in the single digits (and especially below 5%), you are also more likely to get sicker.

There was a time in my life when I could top my diet and was very lean but constantly sick with seasonal colds, viruses and infections. It wasn’t until I began to understand the importance of actively pursuing recovery that I was able to balance hard work days (and workouts) with a healthy diet, better sleep, hydration, and relaxation (relaxation). This improved my immune system. Here are some tips to help put it all together:

Do not eliminate macronutrients. Eat your carbohydrates, fats, and proteins. Also eat foods that are higher in fiber. If you want to eliminate or strictly reduce something, make it a processed food. Here is a great list of foods to help you out. You will find that once you find the right balance of good calories entering your body, you will be able to perform better. You can also better fight disease because of the nutrients you get from the three groups. Make sure you eat enough throughout the time busy work day and workouts before and after training.

Sleep better – this is a MUST! This is especially true if you burn the candle on both ends with manual labor and tough training sessions. Think of every meal and night as a respite from the day’s previous activities and tomorrow’s energy needs.

stay clean. It’s no secret that washing your hands and avoiding putting your hands in your mouth and nose can help you avoid getting sick. After being in public spaces, wash your hands as tomorrow’s cold virus is likely to live on doorknobs, tables, handrails, and almost any surface. Long before COVID, my most important piece of advice for people going to boot camp or basic training, where people from all over the country live together in a confined space, was not to touch their faces and to wash their hands all the time. An upper respiratory tract infection during basic training can set you months back in your ability to maintain your physical abilities, especially as you enter high-fitness basic training for future special ops selection programs.

There’s a fine line between being in advanced fitness and being overwhelmed to the point where recovery is hampered, which affects your immune system as well as overall performance. Reducing your total workload by a few months after shipping so that you can focus solely on your fitness performance and recovery may be the best option when preparing for next year’s departure.

For those who need to add a fitness component as well, start with the basics. Something that develops to a moderate level of fitness over time in frequency and intensity will also help fight off disease better. For starters, it can just be walking and stretching, with more time devoted to your physical health each day. Fitness can strengthen your muscles, bones, and heart health, and can make you more resilient after a cold. But most importantly, with fitness you can do better to fight these infections before they turn into serious infections that require hospitalization.

In all of these issues, persistence wins. Keep moving, eat well, and find ways to reduce stress.

Stew Smith is a retired Navy SEAL and fitness writer who was certified as a Strength and Conditioning Specialist (CSCS) by the National Strength and Conditioning Association. Visit his Fitness eBook shop when you want to start an exercise program to create a healthy lifestyle. Send your fitness questions to [email protected].

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