It helps to understand what is being communicated here. It's not a genuine request for your health status, it's a friendly greeting. The last thing anyone wants in response to "how are you" is a list of everything that's wrong with you. If you struggle to cope with replying "fine" or equivalent, refuse to answer the question and respond instead with something like "hi/hello!". The non-sequitur will jar them for a moment and hopefully they'll learn not to ask dumb questions.