Elite Special Forces units are often assigned to the most difficult missions. They must be prepared for the challenges they will face. This means being skilled and physically fit, but it also means being mentally tough. During most basic-training programs, recruits will be yelled at by instructors, deprived of sleep, and forced to run for miles. Under these difficult conditions, they will be required to make constant decisions. Only the toughest recruits will graduate, and they need certain traits to make it through: intelligence, self-control, courage, knowledge, resistance to pain and discomfort, team spirit, and more.