This study investigates the structural barriers hindering digital well-being among Generation Z (Gen Z) through an integrated lens of Self-Determination Theory (SDT) and Cognitive Load Theory (CLT). Using a cross-sectional survey conducted between June and July 2025, 126 valid responses were collected from Indian Gen Z participants, comprising students and early-career employees. Ten barriers—including lack of awareness, absence of digital literacy, mixed media messages, platform design addiction, and peer pressure—were examined for their interrelationships using Interpretive Structural Modelling (ISM) and MICMAC analysis. Results reveal that foundational barriers such as lack of awareness, absence of digital literacy, and mixed media messages act as high-driving factors, creating cascading effects on dependent barriers like inconsistent sleep patterns, low perceived control, and productivity guilt. From the SDT perspective, these drivers undermine autonomy and competence, while CLT explains how cognitive overload from addictive design features exacerbates maladaptive digital behaviours. The findings highlight the need for multi-stakeholder interventions—spanning policy, education, workplace culture, and ethical platform design—to address root causes and promote sustainable digital wellness. This research advances theoretical integration between SDT and CLT, offering a diagnostic framework for targeted, systemic interventions aligned with SDG 3 and SDG 12.