In the era of perioperative medicine, important advances have been made in the perioperative care of patients, usually within those known as enhanced recovery after surgery (ERAS) protocols. These have led to a decrease in postoperative complications and the duration of hospital stays; however, there is still a lack of preoperative care, which could make perioperative medicine more prominent. Elderly patients, malnourished, anemic and ones with a low physical function before surgery are likely to have sub-optimal recovery from surgery. More importantly, a low functional reserve, together with the inherent physiological stress of surgery, reduces the functional capacity of patients in the postoperative period, meaning that they will not reach their preoperative functional capacity. It is well established that both preoperative malnutrition and anemia worsen surgical results, however, for various reasons, their preoperative optimization is complex. Additionally, both are related to the functional capacity of patients. During the last years, prehabilitation has been incorporated into ERAS protocols. Prehabilitation consists of exercise training and nutritional and psychological support, which increases the physiological reserve before surgical stress. The integration of exercise, adequate nutrition, anemia correction and psycho-social components, with multi-modal optimization in the preoperative period leads to an improvement in the functional capacity of the patients undergoing surgery, with the consequent improvement in terms of outcomes. The present article discusses specific aspects of preoperative care which are not well defined in the ERAS protocols and which represent fundamental shifts in surgical practice, including preoperative nutrition, management of preoperative anemia and prehabilitation.