There are two parts to the nervous system: the sympathetic that controls emotional responses to life as well as larger muscles responses like the direction to move the body from one place to another. This is the part of the nervous system that responds to "flight or flight" if it feels we are in danger. The other part is the parasympathetic that controls all of the automatic functions of the body like heart, breath function, and blood flow.
The sympathetic nervous system when over active feels like being "edgy", "irritated", "not focused"....it's apparent in a body that doesn't know how to be still. Inside of the body a whole set of hormone and chemical reactions happen including the release of stress hormones called Cortisol. When it happens once in a while ( like when there is a near car accident, for example) this cortisol is released in the correct amount to help the body handle the quick muscle contractions that the body responds to an emergency with, as well as redirects glucose to the brain, breaks down proteins into amino acids for body repair, and raises blood pressure if stress happens to lower it (this happens for some people when experiencing great stress). This is all a good natural thing, unless it's happening all the time, like it is for many of us.
Too much Cortisol in the body has the effects of slowing the metabolism, disrupt other hormones, disrupt thinking/and sleep patterns and can be a part of adrenal fatigue and lowered immunity. For many of us, our sympathetic system is over active, responding to everyday activity from a place of flight or flight. It may even be so ingrained as a natural way of being in the world that the tension and excess cortisol is a cocktail the body is used to being in......yet it still slowly takes away from the bodies true state of health and vitality.
When I was running 3 times a week and weight lifting 5 days a week I would train to the point of exhaustion. Everything was about working to get that deep push from within me to get stronger, go further, reach new limits and get more from my body than I ever had before. Going for the burn, working out as hard as possible, fed my ego that wanted to have a perfect body and was willing to do what I thought it took to get it. Meanwhile inside I was flooded with flight or flight cortisol. My emotions flowed, communication and relationships were not nourishing, and my energy fluctuated in highs and lows. I was not feeling healthy....I was driven, but not healthy.
Flash forward to my first dance classes I took in 1998 and the idea of finding movement that was not driven by the "push". To actually balance relaxation with effort. This style of movement in martial arts helps the body to conserve energy and to direct it with clarity. After many years of allowing my body and mind to re-learn how to rest, how to be still, how to move with ease I can now say that my not only am I calmer and much more focused mentally....I'm better at everything I do including physically. My body is more flexible after dancing and yoga for 13 years and able to do a wider range of movements I could not do when I "worked out harder" with traditional workouts. All those years of pounding to "get a workout" have now spiraled out of my muscles and I feel lighter!!!! I am lighter. ( literally!) I sense that my nervous system has re-calibrated to a healthier balance of cortisol and my sleep, emotions, and joy have all been consistent and sustained.
It's so important to notice "how you are training" your body mind as it's easy to fall into mode of working out with intentions to feel better and yet be retraining your nervous system again and again to be in a cortisol whirlpool. Going to the edge all the time and working harder to get through it is a thing of the past. You can reach higher gains, with less effort.....allow the ego and old false beliefs about "what it takes" to go by the way side and practice moving with more attention on what you can relax, soften, release while you move in to your deepest strength, furthest mile, and your dance. Sense your nervous system itself and feel for what a relaxed nervous system feels like. It needs this kind of conditioning/practice to counteract the over firing it's used too. Train your body the way you want to be in life......This is a way to sustain health.