Wearing Thin

I'm locked up here,
I'm locked up tight,
I've cried with fear,
On this cold, dark night,

Where am I?
I try to free myself,
I try, I try,
I'm losing health,

I try to fight,
But I'll lose yet again,
I try with all my might,
But I give in then,

I've given in,
Like so many times before,
My defense wearing thin,
I feel the pain so much more,

Yet again I grab the knife,
And then I slice,
Not knowing I'm risking my life,
But soon enough I pay the price.