Physical fitness is to the human body what fine-tuning is to an engine. When we are fit, we can perform up to our potential. The President's Council on Physical Fitness and Sports defines fitness 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, to bear up, to withstand stress, to carry on in circumstances where an unfit person could not continue, and is a major basis for good health and well-being.'

Physical fitness involves the performance of our heart and lungs, and the muscles of our bodies. Since what we do with our bodies also affects what we can do with our minds, fitness influences to some degree other qualities such as mental alertness and emotional stability.

Fitness is an individual quality that varies from person to person. It is influenced by age, sex, heredity, personal habits, exercise, and eating practices. While you can't do anything about the first three of those factors, it is within your power to change and improve the other three where needed. We'll look at ways to do that in coming weeks.