Help! My Best Friends Think I’m Faking My Disability.

Dear Prudence,
I am currently disabled. I’ve worked my way up to being up and about for an hour to two each day. Whenever I go out, people say the oddest things to me. Today, when I parked my car, a man came up and said suspiciously, “You don’t look disabled.” I said I just had surgery and rushed away. This happens almost any time I use my handicapped tag. Friends will tell me that I don’t look sick, or that I look great, and then take it personally when I say that I can’t go out for long or go to events. One of my best friends today asked if I had just tried increasing my pain tolerance. I never know how to respond, and knowing that these interactions are coming makes me anxious about leaving my apartment. What can I say to strangers who confront me about my disability, and to friends who don’t get it?