Postponing work until you feel like it is a formula for failure. That feeling may never come or its arrival may be so late that the subsequent action is diluted or worthless. There is often a selfishness in that attitude - an idea that the world must adjust to one's personal whims - but there can also be a belief in a certain magic moment that will bring brilliance, insight, and unicorns.
The "feel like it" excuse misses the fact that life's accomplishments tend to come from plodding and not from the sudden dashes. Genius joins us along the way and seldom visits when we're in an easy chair. The journey also has its own attractions and although starting can be difficult, the further along we get, the more we'll start to "feel like it."