My Confusing and Inconclusive Attempt to Define and Measure “Military Mental Toughness”

By Matt Lensing, MTI Contributor

As an instructor at the United States Military Academy at West Point part of my job included assessing and evaluating future Army officers. After three years in the assignment, and my experience as an infantry officer, I felt especially qualified to judge a West Point cadet’s mental toughness during their many crucible events.

These assessments were supposed to be substitutions for combat. Since Army leaders cannot expose students to real-life or death situations, obstacle courses, heights, water, and hand-to-hand combat are used to familiarize future officers with the physical and psychological demands of the battlefield.

During the Survival Swimming curriculum I taught, I passionately defended having students swim in a wave pool with a rifle and thirteen extra pounds of combat gear or jump off a 6.5-meter diving platform. In my mind, these tasks were comparable to facing unknown situations where Soldiers might set aside personal safety to accomplish a dangerous mission. Unfortunately, as I tried to write on this topic, I struggled to find definitive research linking physical assessments to mental toughness, courage, or grit.

 Many people are familiar with Dr. Angela Duckworth’s book, Grit: The Power of Passion and Perseverance. Dr. Duckworth specifically looked at the population that inspired my interest in this topic. She wanted to determine what factors predicted a cadet’s ability to make it through the first summer at West Point known as, “Beast Barracks.” The “Grit Scale,” she developed helped explain why among the approximately 1,000 cadets admitted each year dozens left within days or weeks after arrival.

I was unable to find similar research backing up my claim that overcoming physical challenges in training positively correlated to mental toughness. Instead, the major themes I uncovered were:

  • Fitness tests measure physical performance not mental toughness.
  • Fitness is mode specific and does not directly translate to other activities.
  • The best predictors for future successes are past successes.
  • High fitness levels reduce reactions to stress.

Fitness Tests Measure Physical Performance Not Mental Toughness

 As an instructor, I generalized an individual’s potential based on their performance in the pool. I incorrectly assumed that someone who quit a swim test possessed low mental toughness when in fact they just lacked fitness in the water. Evidence from other military assessment and selection courses helped me realize my flawed logic.

A study of Special Forces Assessment and Selection (SFAS) candidates revealed that physical factors are the greatest predictors for selection. The most influential physical predictors were primarily road march times, number of land navigation points found, and run times. (Farina et al., 2019) This is not surprising as long timed road marches are commonly used in military schools and selections to rank Soldier performance. Successful SFAS candidates had faster times on endurance events, which subsequently counted most toward their overall score.

Although this study looked at other factors, like physiological markers, demographics, psychological predictors, and even grit score, physical performance was most predictive of selection. (Farina et al., 2019) Another Army Research Institute report covering SFAS also notes that physical fitness, “can be improved quickly with the appropriate amount and frequency of work,” so the takeaway for future candidates is to prepare in a manner most like the assessed events. (Beal, 2010)

Fitness is Mode Specific and Does Not Directly Translate to Other Activities

Military leaders love to argue that toughness transfers across domains, but an article in the European Journal of Applied Physiology and Occupational Physiology revealed that any “cross-over,” effect between different modes of exercise is minimal. (Foster et al., 1995) These researchers looked at whether trained runners could improve their running performance by adding cross-training instead of additional running volume. Time trial results revealed that runners’ performance improved with additional swimming workouts, but not to the extent of runners who added more running.

While there are athletes who are high performers in dissimilar sports, more often, specificity is most effective in improving performance in a single discipline. The same comparison could be made about Soldiers. Someone who is exceptional in one physical domain may easily struggle in another. Therefore, military leaders should withhold praise or criticism of someone’s potential after observing just a single physical assessment. Leaders should instead select multiple assessments that mirror the physical occupational demands required of Soldiers in the environments they will operate.

The Best Predictors for Future Successes are Past Successes

SFAS research revealed that past successes were major factors for Soldiers to make it through selection. According to the U.S. Army Research Institute of Environmental Medicine, SFAS candidates who were Ranger School graduates had a 50% greater chance of selection, which is 21% higher than non-Ranger School graduates. (Farina et al., 2019) This statistic makes sense since both Ranger School and SFAS have similar events like road marches, running, and obstacle courses. These candidates also likely understood how to prepare for selection since they had already attended a rigorous Army school. Non-military past successes were also predictors for selection.

Demographic differences in successful SFAS candidates revealed that having a higher education degree increased the probability of selection. More, “years of schooling predicted selection,” but interestingly too much experience was not necessarily beneficial since unmarried candidates without children were more likely selected than older married candidates. (Farina et al., 2019)

Ideally, measuring past success in similar domains will help Army leaders pick better candidates to attend schools, assessments, and selections. Candidates attending a physically demanding course should be most fit in the areas the course assesses. To break the tie between top physical performers, leaders may consider previous successes in the military and then as a civilian. Although research has not determined the best assessment for mental toughness, it does lend truth to the bias that fitter Soldiers perform better.

High Fitness Levels Reduce Reactions to Stress

Research confirms that physically fit individuals manage stress better than less fit people. In The Medical Journal, published by the U.S. Army Medical Center of Excellence (MEDCoE), Doctors Deuster and Silverman report on several studies that confirm improved physiological and psychological benefits from regular exercise and physical activity.

While physical assessments may not directly measure mental toughness, researchers determined that people with regular exercise habits possess traits, “associated with resilience…hardiness and mental toughness.” (Deuster & Silverman, 2013) Attributes of anxiety and depression are also inversely related to maximal aerobic capacity (VO2max), meaning people present less negative psychological characteristics as their aerobic fitness increases. (Deuster & Silverman, 2013) It seems likely that people with elevated fitness levels are less stressed when they experience similar stressors because they already endured a high volume of stress during training.

Although mood improves with increased fitness the research cautions that when someone who exercises regularly cannot maintain their regimen, “negative effects of exercise withdrawal,” will significantly increase as fitness decreases. (Deuster & Silverman, 2013) To reduce negative reactions to stress, Soldiers should maintain consistent physical fitness routines.


I began my research expecting to find that people who did well in physical assessments had high levels of mental toughness. Current research does not directly support this claim. Physical assessments are still snapshots of someone in a particular environment, and under specific conditions. To truly assess someones innate mental toughness, or trained mental fitness, you need to observe them over longer periods.

In my opinion military examples of toughness were prisoners of war and Soldiers from previous conflicts who endured daily shelling and harsh conditions (i.e. the Battle of the Bulge in WWII or trench warfare from WWI). “Tough,” individuals I observed during my career were the members of my unit who demonstrated the same unwavering adherence to standards and a high level of motivation no matter the conditions. After many nights in the field without sleep it is easy for even the most accomplished Soldier to let discipline slip. The mentally tough people I knew were those who did more than just embrace the suck but actually thrived in the worst situations.

I regret generalizing cadets who struggled in physical events as quitters. Some of them were well outside their abilities and no amount of grit or determination would have made the difference. It was invalid to presume that a physical test would measure someone’s mental toughness, or mental fitness.

Future research in grit may reveal what allows some to thrive in harsh circumstances while others succumb to the pressure. In Beal’s research into the predictors of success for Special Forces candidates, he suggests that grit may be more predictive of success in the much longer SF Qualification Course (SFQC) and an entire SF career (Beal, 2010) For the average Soldier however, while fitness is an important metric it does not independently equate to mental toughness. I believe now that repeated successes over time, in a variety of environments, and conditions, are more likely to correlate with high levels of trained or inherent mental toughness.

Matt Lensing is an active duty infantry officer who has served in the U.S. Army since 2007.


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Beal, S. A. (2010). The Roles of Perseverance, Cognitive Ability, and Physical Fitness in U.S. Army Special Forces Assessment and Selection.


Deuster, P., & Silverman, M. N. (2013). Physical fitness: A pathway to health and resilience Effects of heat and strenuous activity: Microbiome and Blood Hemostasis View project Malignant Hyperthermia in Physically Active Populations View project.


Farina, E. K., Thompson, L. A., Knapik, J. J., Pasiakos, S. M., McClung, J. P., & Lieberman, H. R. (2019). Physical performance, demographic, psychological, and physiological predictors of success in the U.S. Army Special Forces Assessment and Selection course. Physiology and Behavior, 210.


Foster, C., Hector, L. L., Welsh, R., Schrager, M., Green, M. A., & Snyder, A. C. (1995). Effects of specific versus cross-training on running performance. European Journal of Applied Physiology and Occupational Physiology, 70(4), 367–372.


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