Health behavior is often positioned between social disadvantage and disease as though it were an autonomous individual response to information, preference, or motivation. That representation is analytically incomplete. Economic insecurity, neighborhood opportunity, social relationships, institutional conditions, psychological load, and access to healthcare can shape which actions are feasible, sustainable, socially supported, or repeatedly disrupted. This article develops a non-empirical conceptual account of how social determinants may become behavior, disease experience, and clinical trajectory without reducing structural inequality to personal choice. It distinguishes structural exposure from psychological mediation, opportunity from realized behavior, behavioral adaptation from health benefit, healthcare availability from usable access, and disease burden from self-management capacity. The proposed account treats behavioral patterns as context-dependent responses emerging within material, relational, environmental, and institutional constraints. It further incorporates reciprocal processes whereby illness can intensify financial and practical disadvantage, thereby altering later behavioral options. Rather than proposing a deterministic chain, the article develops a bounded determinants–behavior–trajectory model in which multiple transitions can be amplified, interrupted, compensated for, or rendered indeterminate by social and healthcare conditions. This framing identifies intervention leverage points while preserving uncertainty about mediation, causality, population transferability, and policy effectiveness.
