Bryon says this after emotionally tending to Cathy. It becomes evident that she is worried about her brother and finds herself challenged by the situation regarding her brother's drug use. Bryon tries to provide emotional comfort through words and actions. Merely being there, expanding his scope of compassion and empathy for someone in need proves to be a challenging reality. It is in this in which Bryon speaks of the emotionally tiring quality of caring: " I was tired. I felt empty and drained. Nothing can wear you out like caring about people." This becomes a critical element in Bryon's transformation. He shows himself willing to submit his being to something larger.
At this moment, Bryon is not so concerned with himself and his own being in the world. Rather, he wishes to be there for someone else. It is here in which Bryon recognizes and acknowledges the caring quality that he lacked in the past. He now has this. His exhaustion comes in being able to care for another person and recognize that his own state of being is not as important as another person. He is exhausted giving himself selflessly for Cathy. It is for this reason that he is physically and mentally exhausted. He understands that emotions are potent elements when they are sincerely experienced, something that has demonstrated itself to him in his emotions for Cathy.