If you rarely show emotion or feeling, that’s stoicism. Your stoicism helps you endure physical or emotional discomfort without complaint, a helpful trait for long car trips with annoying people.
The noun stoicism, pronounced "STOW-ih-siz-um," comes from Stoicism, the ancient Greek philosophical school, which taught that reason could overcome destructive emotions for a more virtuous life. Having great control over one’s emotions and responding calmly to misfortune are the marks of stoicism. If you take the good and the bad in stride without drama of any kind, your stoicism is admirable.