We often find it challenging to maintain or re-start our physical activity programs this time of year.  Mornings and evenings are dark; the days are cold. We are busy at work and at home, making up for time taken off during the holidays.  Where do we find the inspiration to overcome a sedentary lifestyle and kick ourselves into motion?   

I am currently looking for motivation in a book by John Ratey entitled Spark.  Ratey makes a powerful case for the mental and emotional benefits of physical activity.  Recent research shows that fitness is not just about the heart, blood sugar, and body mass index.  It is about the mind.  I plan to share some insights from Spark over the next few weeks.  In doing so, I will only be scratching the surface: I want to inspire you to read it for yourself.

Let's begin with stress.  Stress is a complex response to a variety of stimuli. It can include fear (fleeing), anger (fighting), paralysis (freezing), or hyperactivity (flitting from one thing to another).  Stress responses are designed by nature to deal with an immediate threat and to learn lessons for future reference. The whole complex of chemical and neurological reactions to challenge is intended to leave us stronger and more resilient.  As philosopher Friedrich Nietzsche is credited with saying, "That which does not kill you makes you stronger."

How can we tip the balance toward "stronger" and away from "dead"?  The difference between stress that harms and stress that helps is the level of dopamine found in the brain.  Dopamine is the key to focus, learning, and adaptation; it transforms stress from enemy into friend. 

Dopamine, in turn, relies on a fine-tuned supply of the "emergency" hormone, epinephrine.  With too little epinephrine, the dopamine supply is dormant (and we react passively).  With too much of the hormone, dopamine shuts down (and we freeze, like a deer in the headlights). 

Research shows that dopamine levels are stabilized by physical activity.  The brain interprets increased muscular activity and heart rate as a sign that something's up.  In response, it produces the chemicals of arousal, focus, and learning.  On the other hand, activity defuses the build-up of panic and aimless hyperactivity, achieving the balance that makes us effective.