Thesis: This PhD dissertation aims to document whether personality traits and economic preferences are stable parameters after the occurrence of a significant health event. Given the massive impacts of traits and preferences on life outcomes, it is necessary to provide information as to how much these can change. Results show that traits are slightly modified when individuals face a health event (Chapter 1). Economic preferences, however, do not change after the occurrence of such events (Chapter 2). The finding that preferences are stable might call for a genetic transmission of these parameters. However, results show that economic preferences are not determined in-utero (Chapter 3). Additionally, individuals facing health events are more likely to adopt healthier behaviors than those who do not face such events (Chapter 4). These findings can be used by economic researchers and policymakers. For the former, relying solely upon individual fixed-effect estimations or first difference methods might not account for trait variation. For the latter, changes in traits might modify the willingness to invest in various health, education and labor outcomes, subsequently influencing macroeconomic performance.