The Behavioural Regulation in Exercise Questionnaire (BREQ) is the most widely used instrument to measure exercise motivation under the Self-Determination Theory (SDT) framework. It has been used to track exercise motivation in young, old, active, and non-active samples all over the world. The BREQ consists of 23 items measuring the six behavioural regulations advanced within SDT (intrinsic, integrated, identified, introjected, external, and amotivated). In recent years, the instrument has been incorporated into applied and intervention-based research, serving as an important predictor of physical activity and exercise. Due to limited resources and recruitment challenges in certain populations, assessments using the BREQ must be done more efficiently. As such, there is a need to develop shorter versions of the BREQ that enhance flexibility by reducing participant burden in research. In this study, we created a 12-item BREQ (2 items per behaviour regulation) and a 6-item BREQ (single item per behavior regulation). Using samples of adults (n1 = 323) and students (n2 = 225, n3 = 115), we established the 12-item BREQ and 6-item BREQ demonstrated factor structure commensurate with SDT and evidence of score reliability plus criterion validity aligned with the full 23-item version. The results were replicated in smaller samples of primary care recipients (n = 108), cardiac rehabilitation patients (n = 107), and active women (n = 66). Overall, the findings provide preliminary support for two shorter forms of the BREQ that may be useful for intervention research in applied settings or tracking changes in motives over time using mutli-wave, longitudinal research designs.