The purpose of your physiology is to find your unique niche in the environment around you. This requires an interaction between perception and action. The source of the action is clear perception.
The movie Cinderella Man tells the true story of heavyweight boxing champion James J. Braddock during the great depression. People were motivated to get back on their feet but didn’t really know how to direct their energy. I saw this movie at least 10 years ago and still remember the main character played by Russel Crowe explaining why he fights. He said, “at least I can see who I am fighting.”

There is something very simple and complete about dealing with the environment on that level. In the picture below, all the different detectable qualities in the environment are illustrated, but we an go over each part starting with Power.

Power
Notice the thick green line moving into the brain. That represents the heightened perception necessary to get a high volume of information flowing into the brain. This activates the output like a river flowing from in to out. The green square represents something heavy in the environment. Any form of strength/explosive training increases the ability to burn off steam. However, often the need to burn off steam is based on a distorted processing of one of the other qualities. While power is the highest intensity form of processing, the lowest intensity of daytime processing we call Posture.
Posture

Posture is a state of awareness or awareness which allows you to process mild information without having to think about it. If you go for a walk, you might move out of the way of a tree which is much different than noticing what kind of tree it is. You are vaguely aware of background noise but it should not mess up your concentration. The best example of posture is your actual posture. When standing, you are able to hold your body up automatically without having to think about it so you can talk to someone, etc. If you are overwhelmed by sound or visually or by pain, your posture system is likely extremely weak. The more accurate test of your posture system is your energy levels. Everyone should have good, mild energy all day and sleep all night. Posture allows you to deal with mild, simple things like the silhouette of a picture. Focus is required to see, for examples, the details of someone’s eyes or facial expressions.
Focus

If you just lifted your arm, it shouldn’t require much precision. If you lifted your arm a little, then attempted to move it one degree to the left, then three degrees up, you would be using your focus system which has more precision. Still, a better example of focus would be if you held you arm up and then tried to connect some wires with your fingers. The fingers are wired predominantly for precision.
If you were aware people talking at the table next to you, that information would be dealt with with the posture system, but if you were to try to follow the conversation, you would have to let the information travel up into your cortex which would involve the focus system. The same goes for visual processing. To see a small icon on the phone requires the precision of the focus system.
Endurance

The nail on the picture represents a strong stimulation which may or may not actually cause damage. At first the nervous system will interpret such stimulation as threatening, but with repetition it will figure out whether or not it actually is damaging.
If actual damage is occurring, the body will not get used to it but instead the person should experience escalating pain and that would not activate the endurance system. If, however, the tissues are not being damaged, the body will start to rightly interpret the strong stimulation as not threatening via the production and release of pain killers in the spinal cord. The reason this system is colored red is because it symbolizes and oxygen metabolism which is required for the amount of time it takes to produce the endorphins. This does not only apply to kinesthetic information but visual and auditory as well. Again, our physiology is designed to deal with our environment and there are times, like when running or even swimming in cold water, that we are surrounded by strong, but not actually dangerous input. This has to be matched by a blocking of the input. This is how the serotonin system works which is the reason when running our brains think more idealistic and worries less about what could go wrong.