The overall purpose of this study was to describe the development of a personal development intervention for high-performance sport. More specifically, the primary objective of the study was to present the results of the co-design phases of the intervention development process. The academic research team initiated the process of intervention development, informed by a grounded theory and using a logic model and the Template for Intervention Description and Replication checklist for Population Health and Policy (TIDieR-PHP). During the co-design phases of intervention development, 28 participants (15 athletes, 8 coaches, 5 technical leaders) were engaged via focus groups or individual interviews. We used qualitative description methodology and analyzed data using an abductive content analysis procedure. Participant engagement helped inform the development of the intervention logo, activity bank, delivery format, scheduling, and individualized approach. By the end of the development phase, the intervention comprised five personal development strategies: self-awareness, goal setting, reflecting, perspective-taking, and evaluating. This paper describes the development of a personal development intervention for high-performance sport. It specifically focuses on presenting the results of the co-design phases of the intervention development process. Working collaboratively with end-users and stakeholders can help researchers to develop sport psychology interventions.Taking a sport-specific approach to design interventions can help researchers develop interventions that are tailored to end-users' needs, age, and stage of development within a particular sport.