CBS News 48 Hours takes a look at pain. For millions of Americans, pain is an everyday fact of life, a force that must be dealt with every minute of every day. Whether the pain comes from a poorly understood neurological disease, a migraine, or a blown-out knee, it can be overwhelming. We'll introduce you to people who must deal with tremendous levels of constant physical pain. Then we'll show you some of the new scientific approaches that could help these people live normal lives again. Among the extraordinary people featured on the show: Picabo Street: the charismatic gold medal-winning skier, who badly injured both legs in a race last year. We follow her through her arduous rehabilitation, as she tries to recover her lost strength and mobility. Rebecca Olivares, a 32-year -old businesswoman who has been stricken with reflex sympathetic dystrophy (RSD), an enigmatic disease that sends pain shooting into her legs and leaves her barely able to walk. Both Rebecca and Picabo are being treated by the same doctor, and they strike up a friendship. Over their months of rehab, they become closer and closer. They take a vacation together to a spa in Arizona, and Rebecca decides that she will attempt to scale a 45-foot high rock-climbing wall. Before she'd come down with RSD, she'd been an avid rock climber, and she wants to conquer this obstacle. Amazingly, she does it, and in the process gives herself - and Picabo - a sense of the power of the human will. Robert Garcia, a 33-year-old man who also suffers from RSD. His case is much more severe, racking his entire body with awful pain, as well as tremors and seizures. Having tried all the available therapies, Robert is at the end of his rope. But an innovative doctor, California neurosurgeon Jacob Chodakiewitz, offers to try a new procedure, that will implant an electrode deep into Robert's brain, and a small generator into his chest. Known as deep brain stimulation, this approach can sometimes short circuit the