Just for humor, it's fun to note that she needs to be committed (to an asylum), as well. :)
When I think of commitment and the play Macbeth, I think of Lady Macbeth. She is one committed lady. Early in the play, she receives a letter from Macbeth that details the witches' prophecy and his subsequent new title. Lady Macbeth is thrilled by the news, and she quickly understands that she is one step away from being queen. She commits right then and there to see her husband put on the throne by any means necessary. She's even willing to give up acting the part of a female in order to be more aggressive in her endeavor.
That I may pour my spirits in thine ear;
And chastise with the valour of my tongue
All that impedes thee from the golden round,
Which fate and metaphysical aid doth seem
To have thee crown'd withal. . .
Come, you spirits
That tend on mortal thoughts, unsex me here,
And fill me from the crown to the toe top-full
Of direst cruelty! make thick my blood;
Stop up the access and passage to remorse,
That no compunctious visitings of nature
Shake my fell purpose, nor keep peace between
The effect and it!
My favorite Lady Macbeth line about how committed she is occurs in act 1, scene 7.
I have given suck, and know
How tender 'tis to love the babe that milks me:
I would, while it was smiling in my face,
Have pluck'd my nipple from his boneless gums,
And dash'd the brains out, had I so sworn as you
Have done to this.
Whoa. That is hardcore. She would kill a helpless baby, if it meant that she would achieve her goal.
Macbeth, on the other hand, isn't so committed to killing Duncan. He constantly wavers on the issue all through act 1. He agrees to do it, but then he backs out of it, only to change his mind again when his wife calls into question his manhood.