I don't really like the term "self-discipline." It seems to have overtones of, I dunno, BDSM. I mean, when I was in college I tried very hard to apply self-discipline but in retrospect it seems most of what I ended up with was self-punishment. Which would eventually get me feeling guilty and bad enough that I'd do something, but it also tended to make me feel rotten most of the time. So I reckon that "self-motivation" makes a better paradigm.