Hold in
Definition 1 of 3
Pro Tip 1/3Emotional Control
Use when you need to stay calm and avoid showing strong emotions. 
During the intense game, he had to hold in his frustration.
Pro Tip 2/3Subtle Endurance
It expresses enduring discomfort or unpleasantness quietly. 
She held in her discomfort throughout the long flight.
Pro Tip 3/3Understated Struggle
Can imply an inner struggle that is not visible to others. 
He had to hold in his nervousness before speaking publicly.