Walter Mitty begins as a rather passive character in the short story. He is someone who is pushed around in his real life. However, his daydreams act as a form of development. They gradually give him a sense of confidence that he lacks in his waking life. For example, when he imagines himself as a heroic figure, it starts to seep into his real - life attitude, making him a bit more assertive by the end of the story.
In the 'The Secret Life of Walter Mitty' short story, Walter Mitty's development is a complex journey. Initially, he is completely trapped in a monotonous and unfulfilling life. His daydreams are his only refuge. As he has more and more of these elaborate daydreams, he begins to change. He starts to question his own reality a bit more. His daydream personas, like the fearless aviator or the brilliant surgeon, start to influence how he sees himself. He doesn't become a completely different person, but there is a subtle shift. He becomes more aware of his own desires and the fact that he doesn't have to be so passive in his real life. This new - found awareness is a sign of his development throughout the story.