Lady Macbeth wants power and everything that goes with it. This is why, when she hears what the witches have told her husband, she says: “Hie thee hither, 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.” The “golden round” refers to the crown, and we can see that, without much hesitation, Lady Macbeth has decided that her husband will be king. She even asks to be made less womanly so she can assist her husband in killing the king. When her husband arrives home, she begins discussing the murder of the king without even really asking Macbeth if he has decided.
Later, Macbeth is reconsidering his decision and Lady Macbeth chastises him: “From this time Such I account thy love. Art thou afeard To be the same in thine own act and valour As thou art in desire?” She lets him know she considers him a coward for even thinking about not killing the king. She even tells him that she would kill her own baby before she would break a promise as he has. “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.” She is not afraid to manipulate him in any way possible in order to gain the crown, and therefore, power.
After they have committed the act of murder, Macbeth is horrified by his deed. Lady Macbeth, upon seeing this, is determined to keep him focused on the ultimate goal of becoming king. Macbeth is looking in horror at his bloody hands, and Lady Macbeth tells him: “My hands are of your colour; but I shame To wear a heart so white.” She wants him to snap out of it so they can finish the plan and seize the power.