["Journal of Personality, EarlyView. ", "\nABSTRACT\n\nIntroduction\nResearch on emotion regulation has primarily focused on reactive strategies, while proactive emotion regulation remains less understood. This study investigates proactive emotion regulation through situation selection, where individuals deliberately choose environments to promote desirable emotional outcomes, and examines how this strategy adapts to contextual demands (strategy‐situation fit).\n\n\nMethods\nWe reanalyzed an ambulatory assessment dataset comprising 179 participants and 29,956 momentary observations to test preregistered hypotheses about context sensitivity, strategy‐situation fit, and personality predictors.\n\n\nResults\nResults supported our hypotheses: (a) participants showed greater situation selection when experiencing higher‐than‐usual momentary affective well‐being, indicating context sensitivity; (b) this context‐sensitive strategy use was linked to improved overall affective well‐being, demonstrating adaptive strategy‐situation fit; and (c) higher levels of personality plasticity, but not stability, predicted better strategy‐situation fit.\n\n\nConclusion\nThese findings underscore the adaptive potential of situation selection and highlight personality's role, particularly plasticity, in shaping anticipatory regulatory processes. The results inform refinement of emotion regulation theories and suggest avenues for tailoring interventions to individual differences in emotion regulation tendencies.\n\n"]