There's nothing that does not grow light
through habit and familiarity,
putting up with little cares,
I'll train myself to bear with great adversity.
I've been working with these lines from Shantidevafor about four years now. In order to keep them with me daily, I chant them silently to myself as I brush my teeth every night before bed (for the most part).
Those "little cares" that arrive in our lives have the ability to muck things up greatly, if we can't meet them as they are in the moment. The pain in your back, for example, easily can lead to tension, and then irritation, and then angry acting out of some kind. So it often goes.
Many people come to Buddhism seeking relief from all of this. Seeking something they call peace and calm. But how many of us really understand what calm and peace actually are? It's easy to mistake "relaxed dullness" found through things like television, drinking, eating, and other such commonplace activities, as peace and calm. In fact, such dullness can become so pervasive in your life that you fail to notice the presence of actual calm and actual peace.
I used to meditate like mad, trying to break through the dullness, thinking zazen was kind of an endurance contest I had to win somehow. In this, there was no room for the world to fully enter, no room for the peace and calm that comes when being "confirmed by the ten thousand things" as Dogen once said.