Athletes of all levels, from professionals to amateurs, are looking for ways to improve both performance and health. These not only involves training tasks, but also those aspects that can influence both performance improvement and injury prevention. These aspects are known as invisible training. Invisible training will improve the recovery between sessions, reduce the risk of injury and better assimilate the training. The assumption of these basic measures, together with mental and physical training, will be decisive for sports performance. For example, in endurance sports, training load, nutrient intake and sleep are key factors that modulate immune function, positively or negatively. Regular physical activity as well as a balanced diet and sufficient sleep are associated with improved immune function. On the other hand, prolonged or too intense exercise, energy deficit and lack of sleep decrease the function of the immune system and increase the probability of suffering from infections and pathologies. Therefore, psychological training, rest, nutritional and hydration habits and social aspects will be a necessary activity for the technical managers of a sport, if they wish to achieve medium or long-term physical objectives.