Description of research questions and justification for undertaking the trial Cardiac Rehabilitation (CR) is an effective treatment for CHD and CVD patients, boasting a range of physiological and psychological benefits as well as lowering mortality and risk of secondary cardiac incidents. Despite the aforementioned benefits of CR attendance, uptake and adherence to CR remain inadequate, with cross-cultural surveys demonstrating that only 10-30% of eligible CR patients engage in such programmes. These poor levels of CR participation have been previously attributed to low referral rates amongst healthcare providers, however even within the 30% of eligible patients who become CR participants, the attrition rate is currently 50% and only 20% of attendees report long-term behavioural change. The lack of subsequent engagement with the desired adaptive behaviours is at a great cost to the National Health Service (NHS), with the cost of delivering a "good quality CR service" at £477 per patient and the average cardiac readmission costing £3637. Although physical activity (PA) has been demonstrated to reduce the risk of secondary cardiac incidents, 80% of CR patients fail to maintain regular habitual PA within the first year following a course of CR..