Motivational theories that inform behaviour change (for example, SDT) do not typically feed through to into instructor training programmes, particularly in clinical rehabilitation settings. Therefore, a significant limitation of motivational theory to date is its ability to be translated into clinical practice. Accordingly, it is important that attempts are made to ensure motivational theory is translated effectively in clinical practice in order to increase patients' motivation for physical activity uptake and adherence in cardiac and pulmonary rehabilitation. The current research, therefore, will combine a well-established motivational theory (i.e., Self-Determination Theory) with established motivational practice (i.e., Motivational Interviewing) in an attempt to integrate theory and practice, offsetting Ntoumanis et al's. claims that contemporary motivation research does not typically feed through to instructor programmes.