Macbeth's state of mind isn't good. Firstly, he's absolutely numb with all of the horrific things that have happened - he doesn't feel anything any more. When he is threatened, when his wife dies - he doesn't respond, hardly. He is completely cold:
I have almost forgot the taste of fears:
The time has been, my senses would have cool'd
To hear a night-shriek, and my fell of hair
Would at a dismal treatise rouse and stir
As life were in't: I have supp'd full with horrors...
And this isn't just a local thing. Macbeth's coldness gives rise to a nihilistic philosophy where absolutely nothing matters or is of anything important. This is the bitter, empty talk of a life thrown away, a life wasted:
Life's but a walking shadow, a poor player
That struts and frets his hour upon the stage
And then is heard no more. It is a tale
Told by an idiot, full of sound and fury,
Yet Shakespeare always complicates the tone by balancing one thing with another. Macbeth is still a brave warrior, right to the end:
Blow, wind! Come, wrack!
At least we'll die with harness on our back.
In Act 5, Scene 6, it is Malcolm handing out the battle plans:
You, worthy uncle,
Shall, with my cousin, your right noble son,
Lead our first battle. Worthy Macduff and we
Shall take upon's what else remains to do,
According to our order.
And Macduff goes to England (you see him there in the famous Act IV England scene) to find Malcolm and agree a battle strategy to go forward and "shake" Macbeth's rule. It's a meeting to try and form an alliance to bring Macbeth down and get him off the throne.