Answer:
Forward Iām heavy, but backwards Iām not.
Die without me, never thank me. Walk right through me, never feel me. Always watching, never speaking. Always lurking, never seen.
It cannot be seen, cannot be felt, Cannot be heard, cannot be smelt. It lies behind stars and under hills And empty holes it fills. It comes first and follows after, Ends life, kills laughter.
I fly through the air on small feathered wings, seeking out life and destroying all things.
A great mysterious place that the bold have been known to journey into.
People take me on walks and I run and have fun. What am I?