I should clarify, when I said "My first reaction often is, It's none of your damn business how I am today," that is how I feel but not actually what I say - which is more usually "[bit of a pause] I'm fine, thank you. How can I help you? [in other words, get on with it and stop pretending to be my pal!]"
Grumble, grumble, youth of today, no respect, grumble, grumble...