In its most general meaning, physical fitness is a general state of good physical health. Obtaining and maintaining physical fitness is a result of physical activity, proper diet and nutrition and of course proper rest for physical recovery. In its simplest terms, physical fitness is to the human body what fine-tuning is to an engine. It enables people to perform up to their potential. Regardless of age, fitness can be described as a condition that helps individuals look, feel and do their best. Thus, physical fitness trainers, describe it as the ability to perform daily tasks vigorously and alertly, with left over energy to enjoy leisure-time activities and meet emergency demands. Specifically true for senior citizens, physical fitness is the ability to endure, bear up, withstand stress and carry on in circumstances where an unfit person could not continue.

In order for one to be considered physically fit, the heart, lungs, and muscles have to perform at a certain level for the individual to continue feeling capable of performing an activity. At the same time, since what humans do with their bodies directly affects the state of mind, fitness influences to some degree qualities such as mental alertness and emotional expression.

Physical fitness is often divided into the following categories in order for people to be able examine its components or parts. Particularly, physical fitness is judged by:

1. Cardiovascular endurance: This is the ability of the body to deliver oxygen and nutrients to tissues and to remove wastes over sustained periods of time.

2. Muscular strength & endurance: Strength deals with the ability of the muscle to exert force for a brief time period, while endurance is the ability of a muscle, or group of muscles, to sustain repeated contractions or to continue to apply force against an inert object.

3. Flexibility: This denotes the ability to move joints and use muscles through their full range of motion.

4. Body composition: Considered as one of the components of fitness, composition refers to the body in terms of lean mass (muscle, bone, vital tissue, and organs) and fat mass. Actually, the optimal ratio of fat to lean mass is an indication of fitness. Performing the right set of exercises can help people get rid off body fat and increase or maintain muscle mass.