As these anecdotes indicate, it would be foolish of the injured runner to make no effort to identify the cause of each new injury. However, it is often very difficult to do so, and not uncommonly a prolonged injury will heal on its own before the answer-seeking runner can figure out why it happened. Indeed, T. J. had tried for years to figure out why his knee hurt before I was able to help him. In these common cases, when the cause of an injury is difficult to identify, the runner’s desperately impatient scramble to find a magic bullet adds tremendous stress to the overall injury experience. In fact, in my experience, the anxiety of struggling vainly to solve the mystery of a particular injury often becomes the very worst part of the injury experience. It is better to understand and accept that some injury causes cannot be discerned and to address each injury accordingly. By all means, make every reasonable effort to find the cause, but do not expect to succeed in every case. Be prepared to come up empty and to heal up and return to running without knowing the cause of the pain that made you stop. This mind-set will enable you to get through your injuries with less stress and anxiety. 3. Stubbornness (sometimes) makes small injuries big. When abnormal pain emerges during or after a run, you have two options: You can ignore the pain and continue training as normal, or you can modify your training (take a few days off, move your workouts to a softer surface, or whatever) until the pain goes away. Most competitive runners choose to sometimes ignore their pain. And they get away with it just often enough to keep taking chances. But sometimes they pay a heavy price for their willfulness. An incipient injury that could have resolved itself in less than a week with a little rest becomes a multiweek or even a multimonth setback. A classic case from the elite ranks is that of Mary Cullen, the 2006 NCAA 5,000 m champion. Cullen was training for the 2008 Irish Olympic trials when she developed pain in her sacrum. She tagged it as the type of minor ache that had gone away on its own many times before and tried to train through it, but the pain grew worse and worse. Eventually, weeks after the problem first manifested, she got an MRI (magnetic resonance imaging), which revealed a stress fracture. Had Cullen responded aggressively to the pain when it emerged, she probably would have been training normally again by the time that MRI forced her to stop training and lose all hope of competing in the Beijing Olympics.