You are absolutely right: 

Self Discipline, among many other vital life skills, is not taught in the schools. 

Back in the late eighties, I have had the wonderful opportunity to procur and practise the Neuro-Psychology of Self-Discipline, a self-paced and self-directed, audio-video based program, developed by SyberVision Systems, in conjunction with famed neuroscientist Dr Karl Pribram of Stanford University. 

In retrospect, I must say, the insights and techniques from the program had indeed impacted my professional career tremendously in the ensuing years.