Many people wait for their motivation to strike, before they start a task. But in most cases, this wait is futile, because the motivation never shows up. The fallacy is, that motivation does not just appear some day out of thin air. In most cases, it follows the action, not the other way around.
The Frence say: "L'appétit vient en mangeant.", meaning "Appetite comes with eating.", which is idiomatic for the observation that starting an activity increases one's desire to continue it.
For this reason, procrastination is so difficult to kick, because we start doing something that has little to nothing to do with the actual task at hand, but can not stop any more, because starting the procrastination task made us motivated to continue.
On the other hand, when we really do start the task that we ought to do, we also get motivated to continue, and reach the flow state.