We demonstrate that inducing the construction of a coherent, biodiversity-conserving moral narrative about one’s place in the world can have a lasting impact on pro-biodiversity behaviors. Across two studies (n=447 and n= 509), one-time under-40-minute interventions leveraging two basic cognitive constraints — coherence and causal invariance — led to increased intentions to take biodiversity-conserving actions (Phase 1) and subsequent self-reports of engagement in these actions assessed a year later (Study 2 Phase 2, n=344). This sustained impact contrasts sharply with the typically short-lived (< 2 weeks) effects of pro-environmental messaging. Participants completed exercises implementing the constraints to foster an expanded sense of self. Results show that the expanded self (e.g., agreement with “I imagine myself to be part of a larger cyclical process of living”) mediated reports of engagement in biodiversity-supporting actions (e.g., donating to biodiversity organizations). These effects held across political ideologies, suggesting the approach’s broader applicability to other persuasion topics.