Screw your courage to the sticking place 

Lady Macbeth is telling Macbeth to grow some balls so they can go kill King Duncan.

Macbeth:
If we should fail?
Lady Macbeth:
We fail?
But screw your courage to the sticking place,
And we'll not fail.

Screw your courage to the sticking place by Illegalkitty January 22, 2017