I feel this way. Not everyday, But sometimes. The other day I was severely depressed that I didn't care for anything, and it happened at work around people, and I felt disconnected from reality somehow. In those moments, I just feel everyone else is living but me, everything is moving but me. I have this feeling all the time that I'm not living because I'm not doing the things I would like to do (it's more on the intellectual level accompanied with the emotions that those thoughts generate), but in those moments, as if it becomes closer to reality that I'm not living even though I'm living physically, as if I'm not in the flow of life, if that makes sense. It's hard to describe.