Have you ever wondered what it's like from someone else's point of view? What they think, feel, and what their voice sounds like from inside their body. Have you ever wanted the chance to walk in someon else's shoes?
The thing that comes with walking in someone else's shoes is existencing their experiences. My experiences largely goes with my disability; obviously I have one. I use a power wheelchair which indicates physical impairment, and I wear glasses which indicates a visual impairmen, but so much more is going on. My glasses do not show that I am legally blind, though.
These injuries and/or disabilities are called invisible disabilities; they can not be seen by the eye. You would have to be walking in their shoes to experience it.
This is why you should not judge by what you see. We all slip up and make this mistake, but we should make an effort not to. We don't know why that person needs extra room to move or this person looks fine on the outside but is battling a chronic illness.