The principles of training apply to everyone at all levels of physical training, from the Olympic-caliber athlete to the weekend jogger.
To achieve a training effect, you should exercise often. You should exercise each of the first four fitness components at least three times a week. Infrequent exercise can do more harm than good. Regularity is also important in resting, sleeping, and following a sensible diet.
The intensity (how hard) and/or duration (how long) of exercise must gradually increase to improve the level of fitness.
To be effective, a program should include activities that address all the fitness components.
Providing a variety of activities reduces boredom and increases motivation and progress.
Training must be geared toward specific goals. For example, people become better runners if their training emphasizes running.
A hard day of training for a given component of fitness should be followed be an easier training day or rest day for that component and/or muscle group(s) to help permit recovery.
The work load of each exercise session must exceed the normal demands place on the body in order to bring about a training effect.