The dynamic change in the external environment of Ukrainian enterprises in recent years is characterized by the deterioration of the conditions for the functioning of organizations. Quarantine measures caused by the COVID-19 epidemic have changed the usual conditions of business activity. The military aggression of the russian federation against Ukraine destroys the best strategies and development projects of enterprises. Unpredictable conditions of business functioning in modern conditions require managers to adapt the existing strategy of enterprise development or create a new actual strategy of enterprise functioning in conditions of economic crisis. The personal characteristics of the leader, which directly affect the process of developing the company's development strategy, were chosen as the object of the study. Positive and negative characteristics aimed at understanding the leader's actions, the leader's making of impulsive or measured decisions and their consequences were studied. The work reveals the influence of the leader on the process of forming the company's strategy. In the course of the study, the interpretation of the concepts of «strategic thinking» and «strategic planning», «leadership» and «management» by scientists is given. Common and different between them are established. A number of features that can be used to determine a manager's effectiveness are identified, namely: the manager's personal characteristics, the main organizational factors of managerial effectiveness, and a number of limitations that prevent the full realization of all the manager's personal capabilities. The key elements of the manager's high efficiency pyramid are analyzed. Two principles of maintaining the state of ideal work productivity of the leader are given. Four types of personal shortcomings of the leader and their impact on the process of strategy formation are presented. Mitigating actions to overcome personal shortcomings of leaders are identified. The obtained results can be used in the process of forming an enterprise development strategy based on the leader's personal characteristics and the leader's behavior model.