What is this Doorway?

What is this doorway?
And does someone hold the key? When can I come through?
Who can set me free?
I punch, I scream, I kick the door And still I cannot see.
I’ll fight: I’ll kill until the end
To have my victory.
The years have gone: my youth has died, But not my misery.
There must be more that I can do.
I cannot simply ‘be’.
No longer can I fight, no longer can I kill. Who is this enemy?
Just then the door has opened wide And all I see is me.