This is how I explained it to my wife:
She's overweight and is very uncomfortable about it. It really bothers her because she used to be such an active person but after our child, a knee injury and a spinal injury, she ended up putting on a lot of weight, and really isn't able to do much exercise because it's genuinely painful for her. So this is what I said:
"You know how you look in the mirror and you see somebody else? How you can see yourself there, kinda, but it's not really you and how uncomfortable that makes you feel? Well, imagine that, but you don't even get to see yourself, and imagine that feeling every time you hear yourself speak, or move, or anything else, really. It's like that."