"How Are You?"

"How are you?"  An innocent enough question that often gets asked as I make my way through the day.  The supermarket cashier, the restaurant server, and the bank teller all greet me with this expression.  What I want to answer is "Very well, thank you" or "Great, thanks" but I cannot because I am not.  Right now, the reply "I'm alright" or "I'm hanging in there" is the best I can do.  I feel as if I should elaborate but I do not because at any given moment I am a hair width away from tears.  I know that the time will come when I can truthfully answer as I did before.  Today is just not that day.