Fulfillment is an important theme in the novel. The narrator isn't fulfilled in his life despite having a situation that many people would find pleasing. He leaves the city and finds fulfillment in the jungle of South America. That fulfillment doesn't come from commercial success but rather from actions that feel meaningful. For example, when he finds the instruments he is searching for, he feels that it's the first time he's done something meaningful in his life.

Modern life versus the old ways is another theme in the novel. The narrator feels out of place in the city because modernity separates him from his past. He doesn't fit in; there's nothing he enjoys. He feels almost dehumanized while he lives his normal life. Once he gets to South America, he feels more alive and more actualized. Seeing a place where old methods of doing things are used makes him aware that he feels like he'd given up a part of himself to technology. People there are happy with less and, he believes, better able to remember the past, myths, and history.

Self-discovery is also an important theme in The Lost Steps. The narrator's journey is one of self-discovery. As he gets farther and farther from his old life, he finds himself more. He's happy for the first time in a long time and knows what he wants for the rest of his days. The narrator wants to stay in the small village founded by his jungle guide and live with Rosario, the woman he met on his trip. Ultimately, however, he gives up this self-discovery to return briefly to the modern world to get supplies and put his affairs in order. When he returns to South America, he's unable to find his way back to the village and, by extension, the solid sense of self and satisfaction he had there.