I usually lie, and say I'm OK when asked how I am. I don't think the person asking actually cares usually, and it's just a weird way of saying "hello", rather than an interest in your well-being. Giving some sort of negative response never leads to offers of help or support, but can lead to accusations of being grumpy.
A total stranger once passed me in the street, and as he was walking past he said "Hi. How are you. Great" So he actually gave himself the answer he wanted to hear from me! I was so tempted to stop him, and say "Well actually, I'm feeling pretty bad, and I'd like to tell you about it", but he was walking so fast, and my brain works so slowly, that he'd gone before I could do it
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