The great advances in the medical and surgical management of congenital heart diseases have allowed many children to reach adulthood with often a good hemodynamic result. Nevertheless most of these adults have a limitation of their functional capacity. This limitation is more or less important, penalizes them in their daily life and alters their quality of life. The origin of this limitation is generally multifactorial. It is linked, of course, to the severity of the heart disease and the quality of the operative result. But there is very often a physical deconditioning. It can be secondary to the heart disease but is often secondary to a lack of physical activity. It is the parents, sometimes overprotective, but frequently the doctors who imposed, often wrongly, this restriction. It is essential to take this dimension into account in view of the important benefits expected for health and quality of life. Cardiac rehabilitation is a privileged tool for providing advice in a suitable environment. This requires close collaboration between cardiac rehabilitators and congenital cardiologists to offer appropriate care. We bring here some reflections and the basic elements to guide the re-training of these patients.