Heroes in fiction are stuck in a set of beliefs or attitudes, ways of seeing the world or themselves. The events of the story force them into a moment of realisation which makes them come unstuck. Then they can change.
And only then, once they have changed, can they face the climax of the story. They have tried and tried and tried again and failed every time.
But now that they are unstuck and have changed inside, changed their tack and approach, now they can break through and win the day.