I think many people view motivation the way they might view inspiration or an emotion, something uncontrollable that occurs to us.  They wait for it to strike in the same way they might wait for depression to lift, or anger to recede, or love to bloom or die.  Sometimes it's a long wait.

I view motivation in the category of behavior and action, ie. change your behavior and those actions will affect your emotions.

So when I think on motivation, I think about creating an environment conducive to what I wish to achieve, and a commitment to making it happen regardless of how lackadaisical I might feel.  My initial actions create a mental state more inclined to self discipline.  When we feel disciplined and productive we feel even more motivated to continue.  So we can manufacture motivation in increments simply by deciding to begin.

Sometimes we are naturally inspired into motivation.  This is a gift.

Sometimes we need to pull ourselves from a funk and create it.  This is a decision.