Self discipline is instilled by teaching personal pride and creating an "Esprit De Corps". It is the lack of self discipline and a general feeling of alienation among the yoof of today that is the root of the problem.
The first thing that happened to stroppy teenagers when I signed on was that we were left in no doubt who was giving the orders and what would happen if we didn't obey instantly.
Nowadays the services have gone a bit soft on recruits but they have had to because the kids that do sign up have received little or no discipline at home or at school. I'm sorry but a fifteen minute detention is not going to punish anyone. Especially when the punishment has to be deferred until the following day and is at lunchtime because they dare not make a kid miss the school bus. Result is that the miscreant has to sit in the classroom doing bugger all whilst their classmates are standing outside in the pissing rain because they are not allowed to remain in the premises unsupervised and the teachers insist on having their forty minute lunch break. (The reality of life at Prestatyn High School). Discipline now has to be built up slowly in the Army to get round this problem.
Yes I think that 12 or 18 months National Service would be a good thing and Army Cadet Forces in Schools too ~ but only if the shouting and drilling is backed up by real discipline.