Put on a brave face
Definition 1 of 1
Pro Tip 1/3Emotional Disguise
The phrase often describes hiding true feelings, especially fear, worry, or sadness. 
She put on a brave face when receiving the bad news.
Pro Tip 2/3Situationally Versatile
Can be used in many situations, such as personal challenges or public appearances. 
He put on a brave face for the interview, despite his nerves.
Pro Tip 3/3Not Literal
It's metaphorical and does not involve an actual facial expression change. 
Despite feeling down, she put on a brave face at the reunion.