Well said, Pendragon and everyone.
The important thing I try to remember is that I'm not obligated to engage. I can always nod politely and just be on my way, off hiking my own hike -- not faster because of them, or slower, or more or less worried, or feeling anything at all about them. I don't have to be more than reasonably polite, and I can just go about my business. Which is putting one foot after the other.
Easier said than done, but I'm working on it
!
--Karma