Why do we do PT? To pass the APFT? Or because we're soldiers, and physical fitness is part of who and what we are?

One could argue that the APFT actually gets in the way of physical fitness, in that a large part of PT that is done in the Army is intended to help folks pass or score well on the APFT. SFC Joe S. Davis Jr., MSM, DSL posted the doctrinal and regulatory reasons why we do PT--I think these are spot on. However, I think a large portion of the Army believes we do PT to enable Soldiers to pass the APFT, and because somehow physical fitness has become a proxy measure for leadership.

SSgt (Join to see) in the Army it is the standard to be prepared for combat and the arduous situations you might succumb to. To be physical sound is to be prepared for war along with the mental aspect. FM 7-22 ARMY PHYSICAL READINESS TRAINING
Military leaders have always recognized that the effectiveness of Soldiers depends largely
on their physical condition. Full spectrum operations place a premium on the Soldier’s
strength, stamina, agility, resiliency, and coordination. Victory—and even the Soldier’s
life—so often depend upon these factors. To march long distances in fighting load
through rugged country and to fight effectively upon arriving at the area of combat; to
drive fast-moving tanks and motor vehicles over rough terrain; to assault; to run and
crawl for long distances; to jump in and out of craters and trenches; and to jump over
obstacles; to lift and carry heavy objects; to keep going for many hours without sleep or
rest—all these activities of warfare and many others require superb physical conditioning.
Accordingly, this chapter links Army physical readiness training (PRT) to Army Force
Generation (ARFORGEN).
AR 350-1, ARMY TRAINING AND LEADER DEVELOPMENT
1-2. This regulation prescribes policy and procedure for the conduct of the Army Physical Fitness Training
Program.
Who does AR 350-1 Apply to?
1-3. AR 350-1 applies to all Soldiers, functional branches, units, and operating agencies.
 Physical readiness is the ability to meet the physical demands of any combat or duty position,
accomplish the mission, and continue to fight and win.
 Physical readiness training provides the physical component that contributes to tactical and technical competence, and forms the physical foundation for all training. Commanders and supervisors must establish PRT programs consistent with the requirements in AR 350-1, with their unit missions, and with this field manual (FM). Soldiers must meet the physical fitness standards set forth in AR 350-1 and in the Army Physical Fitness Test (APFT) provided in Appendix A.
 AR 350-1 specifies that physical fitness training is one of the Army’s mandatory training
requirements.
Why is PRT a mandatory training requirement?
1-4. Physical readiness training is a mandatory training requirement because it is—
 Considered by senior leaders to be essential to individual, unit, and force readiness.
 Required by law for all individuals and units.
SSG Warren Swan LTC Stephen F.

A long time ago, I learned a great lesson from a senior NCO. The lesson was....our people are our most important asset, and making sure they take care of their health is the number one way to protect that asset. The PT sessions, the APFT, the body fat standards, the routine physical exams, immunizations, etc., are all just formalized ways of making sure that soldiers take care of themselves.