Great subject!
Prior to becoming ill, I didn't have much use for other people.. the exceptions being my son and wife. I've always had the ability to entertain myself and keep busy with my own projects.
After becoming rather unwell, my human interactions dropped off precipitously. Initially, in the first couple of years, this wasn't a problem. But not having much else to do (nor being able to tolerate any external stimuli), I began working on myself, making myself into a more well-rounded more emotionally available human being. And with these emotions, came the need to share with other human beings. And that's when the loneliness set in.
As I've evolved, I now find much of my joy relating and interacting with other people.. strangers, mostly. This primarily includes doctors, nurses, hospital personnel, caregivers.. etcetera. But I truly enjoy learning how it is that these people operate, how they think and how they feel. And how they see the world. Or determining what it is that inspires or motivates them.
What's funny is that each time I come home from the hospital, I'm on sort of a "high" for the several days that follow. I feel as though I've participated in real life, and real life events.
I'm not sure if anyone can relate to this, my experience, but finding new ways to appreciate humans has been beneficial for me. Much of my life has been spent excluding others, or isolating, but now I seem to be more inclusive.
Additionally..
I also experience joy after having helped others, surviving a difficult experience, or especially after having composed a new song.
When I am detached (not engaged intuitively), I experience little joy. Anything I am doing, or whatever it is that's occupying my time, will not add meaning to my life.