As digital fitness platforms and wellness technologies become the norm in modern health routines, understanding what impacts the user's engagement is key to creating inclusive, ethical and sustainable solutions. Specifically, we explore participation in online fitness environment and related purchasing behavior through the lens of personal traits, digital trust, and motivational drivers. Utilizing 680 respondents' survey data, the analysis uses statistical testing and behavioral segmentation to reveal specific user patterns and preferences. Findings indicate that younger users who are physically active, especially females and those having higher trust in personal data privacy, were more likely to use online exercise programs and to share personal health data. Behavioural segmentation uncovers three distinct user clusters with varying degrees of digital engagement, which demonstrates a considerable diversity in how users engage health-related technologies. In addition, purchases of products in the fitness and nutrition category seem to be motivated not by price or by ethical issues but by financial incentives and gender differentiation. The study emphasizes that privacy and trust, existing workout habits and cost are the prime factors driving the use of digital fitness offerings. In contrast, poor digital readiness, concerns around data management, and the influence of ethical product attributes act as key hindrances in driving sustainable adoption. This study provides a new perspective by combining the behavioral, attitudinal and demographic predictions into one model of engagement with digital fitness products. These findings add to the broader discussions on sustainable consumption, identifying routes for improving health, equity, and digital wellbeing through inclusive and affordable technology uptake.