Despite literature exploring interventions and strategies to encourage exercise adoption and maintenance, the drop-out rate of irregular exercisers, particularly within the first 6 months of adoption, continues to reduce the effectiveness of such interventions. Whilst a body of literature exists exploring the drop-out profile of clinical patients, less is known about the psychological and theoretical differences that discriminate exercise behavior and which could be indicative of susceptibility to drop-out in the general population. The current study examines whether the metamotivational constructs of reversal theory (Apter, 1989), exercise motives and exercise identity can discriminate between males’ and females’ exercise behavior, defined in relation to length of exercise participation, and consistency (frequency of previous drop-out). 973 participants responded to an online survey. MANOVA was used to determine whether exercise length and consistency resulted in significant differences in levels of outcome variables. Where significant effects were identified, discriminant function analysis was employed to determine whether and how the dependent variables were able to discriminate between groupings. Results indicated that differing profiles of exercise identity, metamotivational dominance and motives for exercise could discriminate between females and males who had been exercising for different lengths of time and with different levels of exercise consistency. These findings indicate that specific groupings may highlight individuals who are vulnerable to drop-out so that strategies can be tailored more effectively for these individuals and support more appropriate strategies to develop internalised motivation.