I don't know what this is I've found

I don't know what it is that holds
me in this vice-like grip so cold –
it strangles all the will to live
and breaks the spine that would resist.
It chokes my words and chills my soul
and shatters my once balanced whole:
I'm toppled from my steady stride,
all sense of purpose gone from life.
It leaves me prostrate on the ground:
I don't know what this is I've found.