Krishna: Self-Discipline Defined
As for what is self-discipline, Krishna gave his view (my English translation):
śaknotīhaiva = śaknoti — can + iha — here on earth + iva (eva) — indeed; yaḥ — who; soḍhuṁ — to endure; prāk — before; śarīravimokṣaṇāt = śarīra — body + vimokṣaṇāt — from leaving; kāmakrodhodbhavaṁ = kāma — craving + krodha — anger + udbhavaṁ — basis; vegaṁ — impulsion; sa = saḥ — he; yuktaḥ — discipline; sa = saḥ — he; sukhī — happy; naraḥ — human being
The person who, before leaving the body, endures the craving-based, anger-based impulsions, is disciplined. He is a happy human being. (Bhagavad Gita 5.23)
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Self-discipline usually passes as a social behavior, where a person is willingly law-abiding and takes care to manage in a socially acceptable way. However that varies from society to society because social norms are differ from culture to culture.
Here however Lord Krishna speaks of discipline as the relationship between the self and its craving-based, anger-based impulsions. Krishna did not say that the impulsions were all eliminated.
He stipulated that an inner relationship between the observing self and its impulsions should be in place before the person parts from its material body at death. The person should be resistant enough and expansive enough to contain the impulsions.