Having an "Invisible" Disability while Teaching

I do have some things to say about the AP Institute I attended last week and the last few chapters of Awakening the Sleeping Giant, but those posts are still incubating and this is really on my mind right now.

Let me start by telling you a story:

Once upon a time, last weekend, there was a couple who bought a bed. They'd been sleeping on mattresses on the floor since forever and finally decided to put them on a bedframe. Since they bought the bed at Ikea it took most of a day of frustration to assemble, only to turn out not to fit the mattresses. The mattresses claimed to be queen sized and so did the bed, yet the bed was too big for the mattresses. After some frustration  the couple gave up on having a bed and started to disassemble that one to return to Ikea. It was late and they were tired and frustrated and at one point the wife dropped a large chunk of the bed on her right foot, breaking her big toe. It hurt a lot. A few days later she went to get groceries while wearing the ugly shoe the doctor gave her for her right foot and was relieved at how easy it was to ask for a riding cart when she had such an obvious reason for it.

Enough third person. I've used the riding cart before, and probably should have more often, but normally I feel incredibly awkward asking for it. See, I'm dealing with the acute and temporary mobility issue of a broken toe right now but I also have a chronic issue: rheumatoid arthritis. If you're not familiar with the term invisible disability, I think it can be easily summed up by the image of apparently-healthy-looking me feeling awkward asking for a riding cart at the grocery store because I don't obviously need it.