The aim of this study was to examine the contribution of job demands and resources, as well as personal demands and resources in explaining burnout in helping and non-helping professions. The role of superiors and coworker social support, psychological demands and job control, optimism and perfectionism in explaining burnout at work were examined. Additionally, the mediating role of optimism in the relationship between psychological demands and job control with burnout, as well as in the relationship between social support and burnout, was examined. The research was conducted on 1,089 respondents of which 59.04% participants belong to helping professions and 40.86% to non-helping professions. The measures used in the study were: the Oldenburg Burnout Inventory, Burns Perfectionism Scale, Psychological Demands and Job Control Scale, Social Support at Work and Family Scale, and Optimism-Pessimism Scale. In addition, necessary demographic data and data on job function factors were collected. The results of t-test showed a significant difference between helping and non-helping professions in one dimension of burnout—exhaustion with employees in helping professions experiencing statistically significantly higher levels of this dimension of burnout compared to employees in non-helping professions. The hierarchical regression analysis showed significant contribution of superior and coworker social support, optimism, pessimism, psychological demands and job control, and perfectionism in explaining burnout in helping and non-helping professions. Mediating role of optimism in the relationship between psychological demands and job control with burnout was partially confirmed, with optimism being a significant mediator in the relationship between job control and burnout, but not between psychological demands and burnout. The expected mediating role of optimism in the relationship between superior and coworker social support and burnout was confirmed with high social support contributing to reduced burnout through increased optimism. The results of this research support the Job Demands-Resources (JD-R) model and highlights the importance of incorporating personal demands and resources into this model to better explain burnout. The results imply that recognizing and strengthening employees' personal resources can contribute to the preservation of their mental health within the work environment.