Just-in-Time Adaptive Interventions (JITAIs) are technology designed with the vision of supporting the right person at the right time with the right intervention.  A plethora of studies have explored JITAIs for supporting the users' health, and well-being. However, many existing JITAIs either do not collect user's context and behavior information, or even if they collect the data, they do not leverage the richness of the data while tailoring the intervention content. The formative work of this research suggests a lack of guidance for designing JITAIs that account for the myriad of complications of the users' lives. This project is about advancing the path for designing more user-centered JITAIs that can account for the diverse factors of users' lives. To be specific, this work will provide specific guidelines for designing JITAIs that account for the diverse ways users interact with technology for supporting health and well-being. This work is motivated by the formative studies we have conducted with different populations (e.g., patients with prostate cancer, healthcare providers), the case study I have explored for designing JITAIs (for people with prostate cancer), and a systematic review of current design practices of JITAIs that we have been working on (ongoing). Initial work from these projects shows how user-centered study findings can evolve the design of a JITAI and how interdisciplinary researchers might struggle to be aware of these findings reported in a score of HCI literature. Thiswork will benefit the interdisciplinary research community by bridging this knowledge gap as well as by providing them with concrete guidelines for the user-centered design of JITAIs.