In this study, psychological conditions of pro-health lifestyle behavior have been analyzed. A first research group consisted of 88 healthy people (44 males, 44 females) aged 19-39. Psychological analysis showed a positive correlation between the internal locus of control and adherence to healthy diets; a correlation extending to the knowledge about healthy food. Social exclusion appeared to reduce the possibility of reaping new knowledge about healthy diets and was negatively correlated with the tendency of using healthy diet or dietary supplements. A second group consisted of 70 women aged 20-65. The subjects in this group were oriented towards using a diet which reduces body mass; pro-health both physical and psychological objectives other than body mass reduction were secondary in this study. General self-esteem and physical self-esteem were found to be positively correlated with the involvement in physical activities and satisfaction from dietary intervention. These outcomes were negatively correlated with body mass. The study shows that the efficiency of prevention is related to the locus of control, self-efficacy expectation, faith in the result, and self-esteem. The information about the interconnections among these variables may be useful in building preventive behavioral programs.