Screw up your courage
Definition 1 of 1
Pro Tip 1/3Emotional Charge
Conveys a strong emotion of overcoming fear, used when facing stressful or daunting tasks. 
Before jumping out of the plane, I had to screw up my courage.
Pro Tip 2/3Figurative Phrase
It's metaphorical; you're not physically tightening anything, instead, you're mentally preparing yourself. 
I screwed up my courage and finally asked for the raise that was long overdue.
Pro Tip 3/3Personal Challenge
Often used in scenarios involving a personal battle with fear or hesitation. 
She screwed up her courage and applied for the competitive internship.