It’s not that joining the military lends you discipline, which it does to some extent, but that it allows you to learn to be resolute, which is a different thing. It teaches resolve, that is, in the face of difficulty, obstinance, threat and failure. That’s not the same as discipline, though it’s adjacent to it.

Of course in some ways, this is also self-selection. Those who lack all resolve don’t make it! But being in the service certainly heightened my ability to tolerate intransigence of personnel or materiel until I could prevail over it or, as a paratrooper does, regroup, reorient, and attack from another angle.

That’s something that can’t be taught, but can be learned in the right situations; and the military tends to create those situations.