Flashing metaphor-for-life-in-general alert

Every once in a while I pull or strain some muscle/tendon in my left upper back/lower neck. I think that bit of my anatomy has never quite recovered from a rugby incident that made me unable to breathe deeply for the entire winter of my third year of undergrad. Anyway, the point is, the pain is really frustrating, but not a good reason not to keep on keeping on (even if some of the things I want to do risk aggravating it) and tensing up about it and thinking about how much it hurts just makes it worse - the only possible course of action is to relax, accept that a certain amount of pain is one of the costs of being alive, and keep going.