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Five Thinking Errors That Hurt Your Health

written by Marie-Josée Shaar 11 March 2014

Marie-Josée (MJ) Salvas Shaar, MAPP '07, CPT, has studied, tested, coached, and taught smart health habits for over 13 years. Combining positive psychology with fitness and nutrition, she created a coaching method that builds better sleep, food, mood, and exercise habits, as described in her book, Smarts and Stamina: The Busy Person's Guide to Optimal Health and Performance, which includes 50 practical health-building activities. Today MJ gives keynotes for corporate wellness programs and offers continuing education for wellness professionals, who can license her Smarts and Stamina Online program. Full bio. MJ's articles are here.

The fact that humans survived in a world of more powerful predators is a huge tribute to the potency of our brains. Certainly our claws and jaws aren’t threatening to wolves and crocodiles, our strength is nothing but good entertainment to bears and elephants, and we are barely faster than a turtle to a puma.

But when it comes to the ability to strategize, plan, and execute, no other creature compares, and that brought us to our lofty position at the top of the food chain. Before we got here however, our predecessors had to make countless life-saving decisions, often within a few seconds or less.

Over generations of survivors, humans developed thinking shortcuts which are still very pervasive today. Of these common shortcuts, 5 are very costly to our health. While it is unlikely that we’ll ever break free of their influence, increased mindfulness can alleviate their effects on our thought processes, behaviors, and wellness.

Sunk Costs

We hate failure. The more time, energy, and money we’ve invested into something, the less we want to let it go, explains Daniel Kahneman in his book, Thinking, Fast and Slow. So we watch a late night TV show until the end even if the episode is terrible and we know we’ll suffer from sleep deprivation the next day. We eat the whole Sumo-size dish the waiter placed under our nose, even if doing so requires us to loosen our belts.

Loss Aversion

We hate to lose, or to miss out on something. Kahneman, Knetsch, and Thaler estimate that losses have about twice the psychological impact of equivalent gains. When faced with a choice, we therefore tend to place more weight on avoiding loss than on trying to gain something else. That’s why we pick the happy hour over the gym session, read Facebook posts past bedtime, and cheat on our eating plan when an opportunity arises.

Optimism Bias

We like to think that we are immune to disease or protected from dangers by some invisible guardian angel. William Klein describes a tendency to think “It won’t happen to me,” a state of mind adopted by people who have unprotected sex or who choose the drive-through for daily sustenance.

In my wellness workshops, I often ask members of my audiences how many have below average driving skills. In a crowd of 200 people, I’ll typically see 5 or 6 hands go up, including mine since my husband has told me enough times that it would be tough for me not to know that my driving skills are below average! Similarly, most of us think we need less good sleep, food, mood, and exercise than others to function optimally and stay healthy.

Confirmation Bias

We love for our beliefs and opinions to be validated. This is so much so that we have an internal lawyer, working around the clock to make sure we give more weight to anything that agrees with us and discredit sources that disagree. This is called the Confirmation Bias.

Thus if you’re an avid runner, you’re more likely to find and remember recent information from Miller and colleagues that running doesn’t influence the likelihood of developing arthritis. If you’d rather go blind than go for a run, you’ll find discussions of the dangers of joint overuse, such as that published by PhysioRoom.com, more convincing and memorable.

The Urge to Fit In

Our fundamental need to belong is a powerful shaper of behavior. Just think of all the times you succumbed to regrettable choices due to peer pressure as a teenager (or how difficult it was to resist) and you’ll agree that the desire to fit in impacts us deeply.

Nicholas Christakis and James Fowler review 30 years of data from one of the longest-running epidemiological studies. They found that change doesn’t happen in a vacuum; it happens in netwoks. When we live in a culture that glorifies sleep deprivation, promotes fast food, normalizes high stress and engineers movement out of every activity, our health suffers. But Judd Allen and I have written about how to take advantage of the power of the group to move in the right direction.

Questions to Explore Your Biases

When does your reluctance to let go hurt your health?

When are you consistently deciding against sound health behaviors to avoid some loss, and is it really worth it?

Do you think you’re doing just fine even if sleep deprived, malnourished, stressed, and/or sedentary?

What topics does your internal lawyer most actively pursue? Do they serve or interfere with maintaining a healthy lifestyle?

Who in your network twists your arm away from your health goals? Can you reverse that pressure? Perhaps you could twist their arms in the opposite direction.


I recommend working on one of these mental shortcuts at a time. As prescribed by the Smarts and Stamina health promotion model, choose an easier one to work on first, so you later have the ability to build on your initial victories. Be mindful so you can catch yourself using the distracting shortcut, admit when and how it is leading you astray, then make a smarter choice.


Allen, J. & Shaar, M.-J. (2013). Wellness doesn’t happen in a vacuum. Positive Psychology News.

Christakis, N. A. & Fowler, J. H. (2009). Connected: The Surprising Power of Our Social Networks and How They Shape Our Lives. New York: Little, Brown.

Kahneman, D. (2011). Thinking, Fast and Slow. London, Allen Lane.

Kahneman, D., Knetsch, J. & Thaler, R. H. (1991). Anomalies: The Endowment Effect, Loss Aversion, and Status Quo Bias. The Journal of Economic Perspectives, 5 (1), 193-206.

Klein, W. (no date). Optimistic Bias. National Cancer Institute: Health Behavior Constructs, Theory, Measurement and Research.

Miller, R. H., Edwards, W. B., Brandon, S. C., Morton, A. M., & Deluzio, K. J. (2014). Why don’t most runners get knee osteoarthritis? A case for per-unit-distance loads. Medicine and Science in Sports and Exercise, 46(3): 572-9. doi: 10.1249/MSS.0000000000000135. Abstract.

PhysioRoom.com (no date). Knee Arthritis Explained.

Shaar, M.-J. (2014). Still Accepted But Blatantly Outdated. Positive Psychology News.

Shaar, M.-J. (2014). Smarts and Stamina Health Promotion Model.

Shaar, M.J. & Britton, K. (2011). Smarts and Stamina: The Busy Person’s Guide to Optimal Health and Performance. Philadelphia, PA: Positive Psychology Press.

Weinstein, N. & Klein, W. M. (1996). “Unrealistic Optimism: Present and Future”. Journal of Social and Clinical Psychology 15 (1): 1–8. doi:10.1521/jscp.1996.15.1.1.



Photo Credit: via Compfight with Creative Commons licenses

Human evolution courtesy of bryanwright5@gmail.com
Sunk costs courtesy of Plbmak
Running knees courtesy of Xenocryst @ Antares Scorpii
Peer Pressure courtesy of Travis Nicholson!

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1 comment

Chiamaka Akumuo 17 December 2015 - 8:23 pm

Unfortunately, I would have to say that I have some of these traits. I guess as humans we believe that we are above others and no harm can come to us. One of those traits that was hard and still is hard is the urge to fit. I would say freshmen year of college, I was extremely eager to fit in. I had to come to the conclusion who I was becoming was not me. I thought that urge would end in high school, but it seems like it continues in to the rest of your life. However, I am holding my ground. One of those traits I hope to get ride of is Loss Aversion. We have to learn that we will lose and need to lose to grow.


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