This is a great post, I particularly like this quote:

    "Motivation is the start, but if it’s not solidified into
     discipline,  it usually fades away into regret pretty
     quickly once you realize you never acted on it."

I think it's worth mentioning Stephen Presfield's concept of Resistance here from his book "Do the Work" [1]. I often find myself fired up with a new task, but lacking the follow though that discipline would give me. It's too easy when I want to do something that I don't know how to do (write some Haskell for example) for my little monkey brain to jump off to some interesting shiny thing (HN). Resistance explains this as a way of protecting yourself from the pain of struggling to understand and the risk of failure, by replacing it with something easy and non-challenging.

[1] Read it: http://www.stevenpressfield.com/do-the-work/