Dear saleslady,
You rocked it today, giving me a hand with road-testing the wheelchair and making pleasant conversation -- right up until you asked me what was wrong with me. It's so nice to know that a friend of yours had fibromyalgia and that she cured herself through sheer willpower because, you know, she's a "feisty lady." Gee, if I'd only known that the Power of Positive Thinking[tm] is all it takes to cure this beast invading my brain, spinal cord, fascia, nerves, muscles, and organs, well hell, I'd have been dancing in the streets years ago!
I could give you my moment of sheer rage. I could give you my feeling of inferiority for not being able to just will myself to health by being THAT KEWL. I could give you my resentment of your uninformed snap judgments and smug confidence based on genetic luck of the draw. But you'd have to try a lot harder to earn those. Sorry lady, your opinion just isn't worth that much.
You get this and that's it. These five minutes of posting time. Oh, and a big pair of hairy donkey balls. Go suck on 'em.
Sincerely,
Chronic Pain Wizard