Below, there are definitions of 8 important elements of fitness. (Source: Mark Lauren, You are your own GYM)
MUSCULAR STRENGTH: Your ability to exert a force through a given distance. Muscular strength can be determined by the difficulty of an exercise that you are able to perform for a single repetition. For example, if Jane, with maximal effort, can perform one Classic Push Up and Tarzan can perform a Handstand Push Up, then Tarzan has greater muscular strength.
POWER: The amount of force you can exert in a specific amount of time. Power = Work/Time. If Tarzan and Jane are both able to perform only one Pull Up with their maximal efforts, but Jane is able to perform that one Pull Up faster, then she has more power even though they have the same strength.
MUSCULAR ENDURANCE: How long you can exert a specific force. Jane and Tarzan could compare their muscular endurance by seeing who can hold the peak position of the Pull Up the longest.
CARDIOVASCULAR ENDURANCE: Your body’s ability to supply working muscles with oxygen during prolonged activity. Jane and Tarzan challenge and improve their cardiovascular endurance by performing 200 non-stop Squats together.
SPEED: Your ability to rapidly and repeatedly execute a movement or series of movements. If Jane can do 45 lunges in 30 seconds and Tarzan can do only 25, then Jane has greater speed.
COORDINATION: Your ability to combine more than one movement to create a single, distinct movement. For example, performing a simple jump requires that you coordinate several movements. The bend at the waist, knees, and ankles and then the correct extension of those joints must all be combined into a single movement. Your ability to combine these movements, with the proper timing, into one movement determines your coordination, and in turn, how well you can do the exercise.
BALANCE: Your ability to maintain control of your body’s center of gravity
FLEXIBILITY: Your range of motion. If Jane, while doing a squat and using good form, can go down until her butt touches her heels, and Tarzan can only go until his thighs are parallel to the ground, then Jane has greater flexibility