Yoga and the middle way
If you fall into complete non-doing (not getting up, not drinking water, not eating), you will most probably be dead in about a week. If you do too much (such as running nonstop across the Sahara), you will also find yourself knocking at Death's door.
Either extreme is a movement toward death. The ideal lies somewhere in between. Yoga and health are all about finding balance between opposing forces. Effort and rest. Elimination and assimilation. Yang and yin. Day and night.
When we do not feel, when we are not aware of our inner state, imbalance is the inevitable result. Most of us have so little internal awareness that we don't know we are out of balance until something drastically goes wrong. As an example, most diseases spread in an acidic environment. Because we are not sensitive enough to feel when our bodies are acidic, we continue to consume foods that make our bodies even more acidic. If we could feel more deeply, we would instinctively know when our bodies are acidic, and seek to bring them back into balance.
A body that is in balance craves that which keeps it in balance. On the other hand, a body that is out of balance craves that which moves it further away from balance. Thus, we cannot listen to the predictable wail of our cravings, but we have to feel, and we have to seek guidance, either from deep within or from someone who knows better. Many things that we consider "normal" -pain, old age, senility, and perhaps even death — may actually be avoidable and unnecessary. The aches that we consider a natural function of aging are simply manifestations of imbalance. The inability to move freely, expansively, and with strength has nothing to do directly with aging; it has to do with lack of movement over time, coupled with an imbalanced diet, a rigid mind, and too-brief flirtations with Spirit.
When we are not connected to the light of our source, when our minds are dogmatically opinionated, when our diets are acidic, and when we chronically ignore the protests of our bodies by slouching in chairs all day, our bodies become imbalanced and rigid, and then we blame our lack of mobility on a fabricated villain called aging! Once you are balanced, the work is not over. Whether it is the balance of the mind, the body, or the emotions, balance cannot be achieved and forgotten. When we stand on one leg in Vrksasana, we have to stay vigilant. The moment our attention ceases and we congratulate ourselves for being balanced and upright, we have already begun to fall over. Staying in balance requires as much vigilance as first attaining it. Achieving and maintaining balance are the path, not the destination.