The recent years have been unique and challenging due to the global pandemic changing the way of living, the priorities and the approach taken to tackle several issues. 21st century has already been an age in which global health issues regarding the workforce were intensively discussed, among which burnout can be considered as one of the most severe issues. The COVID-19 pandemic obviously exerted a magnifying impact. Sustainability is nowadays considered in all aspects of business and economics; and it is not possible to address sustainability without taking human factor into account. Employee well-being is the core of any relevant step taken in the way of sustainability. On the other hand, projects and project management roughly correspond to the 20 % of global economic activities, rising to 30% in emerging economies. The paper addresses the topics briefly introduced above, discussing burnout in the context of project management through an extensive literature review, with the purpose of introducing a new and focused definition for project burnout by utilizing existing approaches of sustainability, burnout, the job demands resources model and project complexity. A novel, clear definition for project burnout is an important steppingstone for addressing project performance and for eventually contributing to a sustainable project management approach. As such, useful and applicable practical solutions for sustainability in the project driven businesses are then suggested. Several future research directions are also discussed in the study.