I don't think abled people understands how exhausting it is to have pain. Maybe because their pain is different and usually lasts a few days, but even those few days they're all cranky and annoyed and tired.
But living with pain 24/7 is a completely different thing. Because it's not exactly like "ouchie leg hurt" it's like... You can feel your bones, muscle, tendons, skin, separately hurting in different ways ALL THE GODAMN DAY. ALL NIGHT LONG. on top of that? You gotta smile and be kind, you gotta go to work, you gotta go to school and try to ignore other people making fun of you for using a cane, crutches, wheelchair, stroller, knee braces, etc.
And also, you gotta hear them say "oh but you're too young!" "You don't look disabled to me." "But you could walk just fine yesterday!" And them trying to diagnose you with complete bullshit. Trying to tell you you should try this or do that.
And then when you get home, you don't get to rest, why? Because it hurts. You just spent HOURS in pain and you're exhausted. And now your body hurts even more now. And guess what? You gotta do it all over again tomorrow.
And yet, you're the rude one for not wanting to hangout with them on weekends. For refusing to go hiking or some shit. It's exhausting just to stay awake, even if you sleep you don't get to rest because your body is already using all of your energy trying to keep you alive. And nobody gets it but you.