Pain. Everyone feels pain. Emotional, physical, suffering. It's everywhere, in everything. There is nothing to achieve unless some sort of discomfort is tied to the process of gaining said achievement. Our world was governed by it.
My life was painful, from my perspective. To someone else, it may have been considered paradise. I could see suffering everywhere. When I died, the world I had lived in was full of it. Stuffed to the brim. My peers might have been the ones who could be the most empathetic, and the most ignorant, simultaneously. When I came back, the world was still ruled by fear, by pain. Many things had changed, now, it was only a different strife that plagued us.