screw up (one's) courage
To emotionally prepare oneself to do a frightening or overwhelming task. I'm really nervous about asking Sarah out on a date, but I just need to screw up my courage and go through with it.
screw up one's courage
Fig. to build up one's courage. I guess I have to screw up my courage and go to the dentist. I spent all morning screwing up my courage to take my driver's test.
screw up your courage
summon up all your courage; force yourself to be brave.