Mobile health apps offer a promising approach to promoting holistic healthy behavior change, in the increasing shift toward preventive measures against lifestyle diseases. In this study, we explore the impact of level system structures on the engagement of participants in mHealth apps. Two level-system structures were designed to promote healthy behaviors across physical, mental, and social dimensions. The research used a mixed-method design consisting of a two-arm within-subject crossover experiment, surveys, and interviews. University students and staff members (n=73) were randomly assigned to receive goals in either a single-stream or multi-stream level structure. Participants given the multi-stream level structure were in multiple levels simultaneously, while the single-stream level structure contained one level at a time. The results showed that while participants preferred the multi-stream level structure, there was no significant difference in engagement between the two-level structures. The results also indicated that the preferred configuration of multi-stream level structures did not incentivize participants to engage in goals across all holistic health dimensions. Future research should explore alternative configurations of multi-stream level structures to increase participant engagement.