Every year, I participate in NaNoWriMo (National Novel Writing Month). This happens in November and is thirty days of dedicated writing. Authors with an idea for a novel sit down and daily write at least 1,667 words of a first draft.
This month of concentrated writing time is meant to help authors get the entire story down while the inspiration and ideas are flowing. At the end of the thirty days, you should have a novel-length story, hopefully with a complete story arc (beginning, middle, and end).