Answer:
Fitness today, unlike probably a century ago, is considered as the capacity of the human body to respond and maintain its balance while facing both daily routines that require very little muscular activation, and situations of change with an increase in muscular activation. To say that a person today is fit, is not just to look at how their body looks, whether they look thin, or overweight, muscular or not. Today, fitness is also measured in people whose lifestyle is completely passive and with very little physical activity.
The problem with this scenario is that today we face more situations where lack of fitness appears, than fitness itself. And this does not imply the physical appearance of a person alone; though it gives some indication. Today, the capacity of the body overall to respond to different situations without causing a condition that affects it, nutrition, and other aspects, are taken into account to establish if a person is fit, or not.
As such, fitness testing and the results of those tests become paramount today, as they are the parameters under which people in general, and healthcare professionals, as well as fitness professionals, work to help people to achieve the proper balance for their bodies, and their individual characteristics.