Being in the Army is not like looking like a prick like Arnold in "Commando"...LOL. Jay would not even pass the Basic Fitness to get in. I remember going on long endurance runs and carrying weight, believe me itīs a total diffrent Ball Game. I canīt speak for the American Army but in the British army running and stamina is no 1. We used to call it getting a "Beasting". 
It still is.
When I was in the Marine Corp, they a placed huge emphasis on having high stamina, and running with gear.
Run run run run run, with rifle and gear. Over and over and over.
Pushups, situps, think fighting shape. (Boxers, MMA, add the incresed weight of the gear)
Hike hike hike hike, with full pack, Rifle, ammo, etc. Over and over and over.
Repeat ad nauseum.
Best way I can describe it. We had guys that lifted a lot and some were into bodybuilding, but anything like Jay would have been rediculous and not feasible in the Infantry.
I can only speak about the infantry. I assum its different in pog MOS's.