MARS is an acronym that defines individual behaviors based on four factors: Motivation, Ability, Role Perceptions, and Situational Factors. It helps understand voluntary employee performance and behavior. The four factors are interrelated - weakness in one can impact performance. Motivation refers to direction, intensity, and persistence of mental/intellectual efforts. Ability includes aptitude, learned capabilities, competencies, and ensuring the right person-job fit. Role Perceptions is having a clear understanding of one's role and responsibilities. Situational Factors are external elements like resources, facilities, equipment, organization, and time available.