Exercise Motivation

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One of the most important changes I've made to help me prioritize exercise, in addition to choosing activities I generally enjoy, is to shift my mindset away from seeing it as a chore and more as an essential part of being an inhabitant of a physical body. And that body was made to perform optimally under particular conditions and stresses. I'm reading through Starting Strength for the second time, and the words of Mark Rippetoe are so on point for me. Here, he's talking about strength training specifically of course, but I think everything applies just as equally to cardiovascular fitness:
Physical strength is the most important thing in life. This is true whether we want it to be or not. As humanity has developed throughout history, physical strength has become less critical to our daily existence, but no less important to our lives. Our strength, more than any other thing we possess, still determines the quality and the quantity of our time here in these bodies. [...] .

As the nature of our culture has changed, our relationship with physical activity has changed along with it. We previously were physically strong as a function of our continued existence in a simple physical world. We were adapted to this existence well, since we had no other choice. Those whose strength was adequate to the task of staying alive continued doing so. This shaped our basic physiology, and that of all our vertebrate associates on the bushy little tree of life. It remains with us today. The relatively recent innovation known as the Division of Labor is not so remote that our genetic composition has had time to adapt again. Since most of us now have been freed from the necessity of personally obtaining our subsistence, physical activity is regarded as optional. Indeed it is, from the standpoint of immediate necessity, but the reality of millions of years of adaptation to a ruggedly physical existence will not just go away because desks were invented.

Like it or not, we remain the possessors of potentially strong muscle, bone, sinew, and nerve, and these hard-won commodities demand our attention. They were too long in the making to just be ignored, and we do so at our peril. They are the very components of our existence, the quality of which now depends on our conscious, directed effort at giving them the stimulus they need to stay in the condition that is normal to them. Exercise is that stimulus.

Over and above any considerations of performance for sports, exercise is the stimulus that returns our bodies to the conditions for which they were designed. Humans are not physically normal in the absence of hard physical effort. Exercise is not a thing we do to fix a problem – it is a thing we must do anyway, a thing without which there will always be problems. Exercise is the thing we must do to replicate the conditions under which our physiology was – and still is – adapted, the conditions under which we are physically normal. In other words, exercise is substitute cave-man activity, the thing we need to make our bodies, and in fact our minds, normal in the 21st century. And merely normal, for most worthwhile humans, is not good enough.

Rippetoe, Mark. Starting Strength. The Aasgaard Company. Kindle Edition.