Core life activities index (CORE)
The Core Life Activities Index (CORE), developed by the current research team, was administered to assess the level of vitality in daily activities over the past week. This measure includes five questions about engaging in everyday activities such as sleep, eating, and physical activity, scored on a five-point Likert scale (1 = never, 5 = always). Higher scores indicated greater engagement in daily activities, which can be interpreted as higher vitality. CORE has previously shown good internal consistency in a preliminary study on the psychological effects of COVID-19 in Korea (Cronbach’s α = 0.77)