How are you? the greeting that everyone knows isn't usually a real question. Everyone expects the usual "Fine, and you?" The typical North American exchange. Everyone knows that "how are you?" really doesn't imply any interest in the other person's well being. This is why I'm seldom honest when asked. When a person stops me and asks "really?" after I answer "fine" I'm often moved to tears. To have someone care enough to want to know how I'm really doing is a gift.
I often wonder what people would think if I gave an honest answer. If I answered every person honestly who asked "How are you?" I'd never get anything done. Not to mention that people would be sure to stop asking me. I hurt. Every day I hurt. There is never a time when I don't hurt. So what do I say when people ask "How are you?" My usual answer is just like everyone else, "fine." I let myself go silent because I don't want to seem like a whiner.
On particularly bad days I'll usually say something along the lines of "I'm here" or "I'm alive" or "surviving." My own private code that few understand to mean "Please just shoot me now and put me out of my misery."
On my good days I'll usually answer "I'm good."
An invisible illness is easy to forget. If you don't know that the person next to you is dealing with a chronic illness you may not realize how well she is hiding her pain.