The physical aspect of it. The DoD did a survey of the USMC, USAF, Army, and Navy's Basic training, and they concluded that Mentally the AF had it down, and USMC came in 2nd, Army I believe was tied at 2nd or might have had 3rd, and Navy came in last. Physically the USMC had 1st followed by the Army, then the AF, then Navy. You should be able to find it if you look it up.