Fitness can be described as the ability to perform daily tasks vigorously and alertly, with energy left over for enjoying leisure-time activities and meeting emergency demands. It is the ability to endure stress, to continue on in circumstances where an unfit person could not continue and is the basis for good health and well-being.

Physical fitness involves the performance of the heart, lungs and the muscles of the body. What we do with our bodies also affects what we can do with our minds.  Fitness can influence, to some degree, mental alertness and emotional stability.