Public health emergencies such as the COVID-19 pandemic pose daunting challenges to both policymakers and citizens. Social distancing measures have been found to adversely impact mental health. In this study, we sought to identify those who thrived throughout the worst wave of the COVID-19 pandemic in Hong Kong. We used a 30-day diary dataset that captured the daily hopefulness ratings of 611 participants (15,575 observations) together with their Big Five personality scores. Hopefulness scores remained stable throughout the enforcement and lifting of social distancing. Individuals who were emotionally stable, extraverted, open to experience, and conscientious felt hopeful overall. In contrast, agreeable individuals, who tend to hold a positive view of human nature, did not feel hopeful during the 30-day period. Our findings suggest that people with agreeable and positive traits do not retain their hopefulness during an actual health crisis and might be at risk of poor mental health, suggesting the need for intervention.