When the witches tell Macbeth that he is going to be king, he reacts by writing her a letter. This seems to indicate that she is highly interested in his advancement. She tells him not to worry, to be courageous, and to pretend to be Duncan’s friend.
In Act 1, Scene 5, Lady Macbeth suggests that her husband pretend to be Duncan’s friend while planning to kill him. She tells him, “bear welcome in your eye” so Duncan is not suspicious.
Your hand, your tongue; look like the innocent flower,(70)
But be the serpent under't. (p. 20)
Macbeth does not seem convinced. He tells her they will talk about it later. She knows that she will win in the end, because he seems to do what she says.
In Act 1, Scene 7, Macbeth asks Lady Macbeth what will happen if they will fail. She basically tells him to suck it up and be a man.
But screw your courage to the sticking-place,
And we'll not fail. (p. 24)
This quote demonstrates that Lady Macbeth is spurring Macbeth on, and without her urging he might be too wishy-washy to actually do it. He worries about what will happen, and she just tells him he needs courage and he will succeed.
In Act 2, Scene 2, Lady Macbeth also encourages her husband when he has killed Duncan and he worries that he heard voices telling him he “murdered sleep” and he cannot say the word “amen” (p. 30)
You do unbend your noble strength, to think
So brainsickly of things. (p. 30)
She encourages him not to dwell on his anxiety. She is more concerned that he become king. She encourages him even when he has self-doubts.
Quotes from: http://www.enotes.com/macbeth-text