Background: Cardiovascular diseases (CVD) are a leading cause of premature death worldwide. International guidelines recommend routine delivery of all phases of cardiac rehabilitation (CR). Uptake of traditional cardiac rehabilitation remains suboptimal, as attendance at formal hospital-based CR programs is low, with communitybased CR rates and individual long-term exercise maintenance even lower. Home-based CR programs have been shown to be equally effective in clinical and health-related quality of life outcomes and yet are not readily available. Objective: Given the potential that home-based CR programs have, it is important to explore how to appropriately design any such intervention in conjunction with key stakeholders. The aim of this study was to engage with individuals with CVD and other professionals within the health ecosystem to (1) understand the personal, social, and physical factors that inhibit or promote their capacity to engage with physical activity and (2) explore their technology competencies, needs, and wants in relation to an eHealth intervention. Methods: Fifty-four semistructured interviews were conducted across two countries. Interviews were audiotaped, transcribed verbatim, and analyzed using thematic analysis. Barriers to the implementation of PATHway were also explored specifically in relation to physical capability and safety as well as technology readiness and further mapped onto the COM-B model for future intervention design. Results: Key recommendations included collection of patient data and use of measurements, harnessing hospital based social connections, and advice to utilize a patient-centered approach with personalization and tailoring to facilitate optimal engagement. Conclusions: In summary, a multifaceted, personalizable intervention with an inclusively designed interface was deemed desirable for use among CVD patients both by end users and key stakeholders. In-depth understanding of core needs of the population can aid intervention development and acceptability.