Even astronauts have shown similar loses when subjected to weightlessness. Weight bearing exercises such as walking, running and weight training will help keep your bones strong and resilient. Improves immune function - The immune or lymph system has about 4 times as much fluid as the circulatory system, yet it does not have a heart to pump around the fluids. It is physical movement and diaphramic breathing that is responsible for the movement of the lymph fluid. Lymph fluids surround each cell, and it is through this medium that the nutrients and waste are exchanged.
Exercise helps expedite the movement of the nutrients to the cells and the toxins from the cells.
This is why I believe that cancer risks decrease with higher levels of fitness. Increases life span - Fitness increases life span and the quality of those extra years. Controls weight - You cannot have long term success in weight loss without exercise. As noted, the fitter you are, the less chance you have of becoming ill. Consider the health care crisis we are facing and think of the savings fitness can have to both to yourself and your federal, state or provincial governments.