The beauty of emotion is that it can be manipulated by internal and external stimuli—circumstances that amplify what a character is feeling. Hunger or extreme heat can increase strain and deplete the body to the point where goals seem insurmountable. Stress can unbalance the most stable of characters, opening them up to raw emotion, rash decisions, and, ultimately, mistakes that send them on a crash course with disaster.

Amplifiers also can evoke memory for the reader because of their commonality. At some point, every person has felt a burst of energy that propels him to tackle a task; they have experienced pain that sends a jarring throb through flesh and bone. Universal experiences like these help forge an empathy link between reader and character.

As writers, it is our job to turn up the heat and make life hard for characters. Written thoughtfully, the difficulties that arise from an amplifier will trigger a stronger emotional response that reads as authentic and credible. Compromising your character’s physical and mental states also creates tension, planting doubt in the reader’s mind about the hero’s ability to succeed.