Why is cardio-respiratory endurance regarded as the most crucial component of fitness?

Who claimed that was the most crucial?

There are several aspects of fitness that, in my opinion, are all equally vital.

Cardiovascular (aerobic) endurance - because it affects your lungs and heart, this element has a significant impact on your overall health. You must be able to move oxygen throughout your body, and the more you can do so, the more energetic and fit you will be.

- Muscular stamina.
- Muscular flexibility and mobility.
- Composition of bodily tissues.

Some of the other, albeit not so important, fitness components include:

- Agility.
- Stability and balance (static and dynamic).
- Coordination.
- Reaction time.