Source : Webster's Revised Unabridged Dictionary (1913)

Self-discipline \Self`-dis"ci*pline\, n.
   Correction or government of one's self for the sake of
   improvement.

Source : WordNet®

self-discipline
     n 1: the trait of practicing self discipline [syn: {self-denial}]
     2: the act of denying yourself; controlling your impulses [syn:
         {self-denial}, {self-control}]