A 56-year-old man with non-ischaemic dilated cardiomyopathy, who was receiving guideline-directed medical therapy, was admitted to the cardiac department for management of congestive heart failure. Following the resolution of his congestive symptoms, a baseline cardiopulmonary exercise test was performed, which yielded a VO2peak of 11 ml/kg/min. On account of a left ventricular ejection fraction of less than 35% and the presence of left bundle branch block on the electrocardiogram, with a QRS duration of 170 ms and sinus rhythm, a cardiac resynchronisation therapy defibrillator (CRT-D) was implanted. Four weeks post-implantation, his exercise capacity improved to 12 ml/kg/min, indicating an increase within the lower threshold documented in the literature (1.1–2.3 ml/kg/min). The patient was then enrolled in a 6-month cardiac rehabilitation programme aiming to further improve exercise capacity. Initially, he did not tolerate physical training due to the loss of biventricular pacing during exercise. Following the adjustment of the AV delay from 170 to 130 ms, based on an intrinsic PR interval of 150 ms, sustained biventricular pacing was successfully maintained throughout exercise. After completing the rehabilitation programme (at 6 months), his VO2peak increased to 15 ml/kg/min, indicating a 26.6% improvement from the baseline. In conclusion, cardiac rehabilitation is a crucial component of care for heart failure patients undergoing cardiac resynchronisation therapy, as it further improves exercise capacity. Maintaining biventricular pacing during exercise is essential for optimal outcomes.