You're never too old to feel left out apparently- it's not just for awkward middle school moments! As a rule I don't usually feel like an outsider when amongst my friends, but lately I'm more aware of the rift. I'm not one to bring up medical issues unless asked, assuming that unless there is some invitation to share that people would rather not hear about it. That is just my style and I'm not about to change things at this stage in the game. Anyone who knows me well understands this, I figure.
I truly understand that it isn't always about me. Just because I have serious medical issues that nearly always trump whatever others have going on, doesn't mean that my problems are worse, per se. I'm empathetic (I hope!) and try never to say "oh yeah, you think that's bad? listen to this!" In all honesty, I'd much rather listen to friends' problems which I consider much more interesting my own. That being said, I am somewhat sensitive to the fact that there is frequently no inquiry into my health, what is going on for me even a "how are you feeling today?"
I've reached a point in my life where I'm not able to easily participate in many of the activities that others in my social circle find fun. It's more difficult to get around with the O2. I can't be as active and my energy is lower. I need to avoid smoke. I'm ready to go to sleep when, by most people's standards, the evening is just getting interesting.
So what's the answer? I don't want friends to have to alter plans in order to include me. Why should their social lives and fun be penalized because I can't keep up? So do I politely smile and say "no thanks" when invited, or would I rather that they didn't mention activities I can't be involved in at all? Not sure. It's easy for me to see that isolation and pulling away is the path of least resistance, being around others who can understand first hand what this feels like is much easier and more comfortable. I know many people who wrestle with this issue and have yet to come across a good answer to the question.
As with most things, a work in progress. Here ends my mental dump and sort.