" … but friends run away when they have to deal with mobility issues or other health issues."

That is too often true! I have to admit to once being that sort of friend. A person with whom I worked for many years and with whom I became very close (luckily, he still is my friend) has macular degeneration as well as other medical issues. He's in his late 80s, lives alone, and doesn't drive. A half dozen of us (his friends) took turns taking him to his doctors' appointments. One by one, they made excuses and stopped taking him. I was the last and soon found myself making excuses, too. I'm not proud of that but am grateful that was several years ago, and I'm no longer that way. It seems what happens is the friends begin to see only the disability and no longer the person. I wish there were a way to change people's way of seeing their ailing friends.