This study aimed to explore and understand the self-coaching experience process of middle-aged women who participated in an online coaching program. Data were collected from nine theoretically sampled participants via in-depth interviews and documents. Following the systematic grounded theory method, the analysis was conducted in three phases: phenomenon understanding, categorical relationship, and theory integration, deriving multiple concepts and 20 categories. In the categorical relationship analysis, relationships among categories were explored through causal, processual, and micro–macro analyses. In the theory integration analysis, the core category “Self-dialogue for Cultivating One's Life” was derived, and a theoretical model was developed by integrating and elaborating the findings. The results are as follows: First, the online environment of the coaching program served as a foundation that enabled middle-aged women to experience self-coaching and engage in immersion within a psychologically safe setting. Second, the dual cyclical structure of ‘questioning–reflection–practice’ and ‘recording–sharing–feedback’ served as an important driving force for deepening the process of ‘observation–recognition–acceptance–regulation’. Third, the routinization of self-coaching was found to be connected to changes in self-efficacy, psychological well-being, and quality of life. Fourth, changes through self-coaching began with restoring the relationship with oneself and gradually extended to family, workplace, and community.