In the TAS, our main character has a need or desire which outside forces try to prevent, challenging him to overcome adversity to achieve his goal. Sounds like a nice, simple formula, doesn't it? However, without the critical element of STRESS, the storyline falls flat.
Little Johnny wants a cupcake. His mother says no. He waits until she turns her back and then takes one anyway.
Can you see it? No Stress = BORING. Johnny wants something, but he isn't stressed about it. The reader could care less whether he achieves his goal or not, because the stakes are nonexistent.
But let's look again, this time applying factors to cause stress:
Little Johnny has diabetes, and hypoglycemia is setting in. He doesn't want that cupcake, he freaking needs that cupcake. He's shaky, sweating, and his limbs aren't cooperating like they should, and he knows that if he doesn't get sugar STAT, it'll be lights out.
As readers, this situation has our blood boiling. Mom's obviously sadistic, not handing the sweet over. If it was up to us, we'd call Social Services and cheer as she's charged with neglect and failing to provide the necessities of life. Sadly, it isn't up to us, so all we can do is watch, helpless, and pray Johnny is strong enough to figure out what to do.
The application of stress has achieved something incredible: the reader now cares about Johnny. They are invested in his situation and riveted on the outcome.
With the stress level maxed, the stage is set for action. The stakes are high. What will Johnny do to survive? How will he overcome his weakness and defeat this older, stronger mother-villain? How will he push aside the emotional connection of being her son to save his own life?
It doesn't matter what the situation is, STRESS is what pushes your main character to ACT. It can force them to go against their own nature or beliefs, to meet challenges, overcome obstacles and face danger. Stress creates tension, which leads to conflict, so don't be afraid to amp up the stress. The higher the stress, the more elevated the stakes are, laying the groundwork for a compelling story that will captivate your reader and make them feel invested in the outcome.