Remember that plot diagram you learned about in English class? The one where the rising action is depicted like a mountain, ascending at a steep angle until it reaches the summit where the climax is? Mountain climbing is an apt metaphor for what your protagonist is doing; in the beginning, something makes him decide to climb the mountain (inciting incident) and off he goes (point of attack.) The terrain isn’t terribly strenuous at the outset, and your hero has plenty of strength and stamina. But by the time he reaches the top, odds are, he’s been pushed to–or in some cases, past–his limits, but he still struggles on because he wants to get to the top and see the view.
This has important implications for you as a writer when it comes to helping your character grow and building tension in your script. The higher up the mountain your character climbs, the further down he will fall if he slips. As the playwright, your job is to make his climb as difficult and “deadly” as you can, without killing him off (Unless that’s what you want to do.).
As a good playwright, there are times when it’s important that you tempt him to turn around and go back, and there are times when you create circumstances where turning around is not an option. Moreover, there should be situations in which he fails and falls flat on his face. Make him work for every single success he gets; make him earn the right to go on. The way you do this is by raising the stakes–by increasing not only the rewards a character stands to gain if he succeeds, but perhaps more importantly, increasing the personal risk (what he stands to lose) if he fails. When you character faces trouble, ask yourself, What would make this situation worse? Then ask yourself, What would make this situation even worse? Finally, ask yourself, What could make this situation even worse than that? And then, throw it at him. By the time you reach the climax, the potential outcome of the situation should matter more than life itself.