Describe how being fit can help your immune system?

Being physically fit allows the body to function at peak
capacity, with all systems functioning effectively, including circulation, respiration,
circulation, digestion, elimination and neurological function. Being overweight or obese
places strain upon the bones, the heart, the joints and often the digestive system
functions less efficiently in obese persons due to the presence of toxins and/or poor
diet. Lack of physical fitness may also mean the body's circulatory system is not
working efficiently, since lack of exercise means less oxygen moving through the blood.
The organs of elimination also function less efficiently when there is a lack of
physical activity as well: the skin is an example of one of the organs of elimination
that benefits from exercise. The body needs to perspire to eliminate toxins to help
protect against infection, and lack of exercise usually means less opportunity to
perspire. Exercise also helps regulate body temperature by temporarily raising it and
then forcing the body to perspire to cool off, and the regulation of body temperature
helps bolster immunity.