Endorphins (“endogenous morphine”) are endogenous opioid peptides that function as neurotransmitters. They are produced by the pituitary gland and the hypothalamus in vertebrates during exercise, excitement, pain, consumption of spicy food, love and orgasm, and they resemble the opiates in their abilities to produce analgesia and a feeling of well-being.
Emphasis added and Wikipedia footnotes removed by yours truly.
Sometime ago I referred to drug use as a shortcut to pleasure. The Wiki I quote above strongly indicates our very own bodies produce opiate like substances to help our bodies cope with stressful situations — namely strenuous physical activity. When God was forming us (Open up God’s toolbox and in it you see evolution) it became apparent that humans need to bust their @$$e$ from time to time and that endorphins helped us through those times. Whether it was hustling across the African savanna chasing an antelope down, hustling down the road to make spot X before your adversary, or splitting a cord of firewood; those who can squirt out a bit of endorphins probably did better at it and actually may have even come to crave the exertions.
Of course, dude coming back to the camp with an antelope on his shoulders is more likely to feed his family than the one who did not come back with an antelope. So being able to endure and in fact seek out the exertion gave one an edge on survival and propagation of the genetics.
In fact, the discussion of runner’s high in that same Wiki also refers to other chemicals released by the body during strenuous exercise that mimic other drugs. Research such as this makes one thing patently obvious, drugs do what they do for a reason and that most all drug buzzes can be replicated without the drugs, but it takes effort.
In my case the effort is to get back into shape!