The Kidneys house what in called our Yuan Qi, or source energy. The Yuan Qi is the neo-natal Qi supplied to us from our parents at the time of conception. Its quantity is set at birth. As a result we can never increase our Yuan Qi, however we can conserve it.
Think about it this way. Every action costs a certain amount of Qi. If we eat right, exercise, get enough sleep, manage our stress, and keep our bodies healthy, then we pay for our activities with post-natal Qi, ie, the Qi we produce from the food we eat and the air we breath. In this situation, we only need make a small withdrawal from our Yuan Qi. If on the other hand we fail to take care of ourselves, then to make-up the difference our body will draw a larger proportion from our source Qi. Thereby decreasing our Yuan Qi at a faster rate.
What’s the problem with this you might ask? When our Yuan Qi is depleted, our lives are over. So, taking care of ourselves and nurturing our Kidneys in this season is not only about living a healthy life, it is about living a longer life.