What makes the threshold different—a defining moment in the hero’s journey—is that once you cross the threshold, you cannot go back. To cross the threshold is to commit yourself completely, wholly, and without limitation.
Sun Tzu, a sixth century BCE Chinese general and the author of The Art of War, said, “When he has penetrated into hostile territory, but to no great distance, it is facile ground.” Ninth century AD Chinese poet Tu Mu added, “When your army has crossed the border, you should burn your boats and bridges, in order to make it clear to everybody that you have no hankering after home.”
As long as you give yourself an “out,” you will not give everything you have.