The 5 components of physical fitness Physical fitness is your ability to carry out tasks without undue fatigue. Learn about the components of physical fitness : cardio-respiratory endurance, muscle strength, muscle endurance, flexibility and body composition and why they are important. that are most important, directly related to one's health, and can be directly measured are: 1. Cardiovascular Endurance Cardiovascular endurance is the ability of the heart, lungs and blood vessels to deliver oxygen to your body tissues. The more efficiently your body delivers oxygen to its tissues, the lower your breathing rate is. While this may help you get a little more bottom time from each tank of air, the real benefits are being more relaxed during each dive, experiencing less fatigue and being better able to respond to challenging currents, long swims and any emergencies that may arise. Essentially,...