From the best episode of the podcast Scriptnotes, I keep coming back to this nugget from Craig Mazin about the “low point” that often comes at the end of the second act of a screenplay:
The low point isn’t always, “Oh boo-hoo me.” For me, the low point is the character has lost his way. The character is separated from the confidence that they had in the beginning of the movie that this is the way the world is and this is who I should be. They have not yet, however, gotten to a place that they will eventually get to where they have a reformulation of, “This is the way the world is and this is how I think I should be.”
William Comfort Anderson 