Those who do not use their limbs every day will realize a weakness when they do attempt to exercise. The veins and muscles are not in a condition to perform their work and keep all the living machinery in healthful action, each organ in the system doing its part. The limbs will strengthen with use. Moderate exercise every day will impart strength to the muscles, which without exercise become flabby and enfeebled. By active exercise in the open air every day, the liver, kidneys, and lungs also will be strengthened to perform their work. Bring to your aid the power of the will, which will resist cold and will give energy to the nervous system. In a short time you will so realize the benefit of exercise and pure air that you would not live without these blessings. Your lungs, deprived of air, will be like a hungry person deprived of food. Indeed, we can live longer without food than without air, which is the food that God has provided for the lungs. Therefore do not regard it as an enemy, but as a precious blessing from God. CH 54.1