Your quote, "I often tell myself that happiness is a mood and not a destination," is spot on. It can be so hard to be happy amidst horrible or unfortunate circumstances, but I have seen people do it and know its possible. Just keep reminding yourself of what you already know. We all need these reminders sometimes.
@jbn has a contest going for inspirational quotes here. Based on your words above, I think you would do really well. :)