A sad little number – though I feel that I need more detail to really empathise with whoever is doing the running. I’m dead to them…but I was never alive is an interesting line.

It’s definitely sad, and I’m not sure how to add without changing the tone or adding a counterpoint.

Flipping the last two lines might work for a nice sense of symmetry and could flow as well or a bit better.

I agree with thx about those last two lines. it’s all coming down to the running, leave that as the focused, closing thought.
It’s pretty good though. I would move some words a little, but that’s personal preference, not because it’s better really.