What is the opposite of wearing your heart on your sleeve?

The opposite of wearing your heart on your sleeve typically refers to someone who is more guarded, private, and reserved with their emotions. Instead of openly expressing their feelings and vulnerabilities, they may keep them deeply hidden and only share them with a select few. This person may be seen as more stoic, composed, and difficult to read, as they tend to value emotional independence and self-control. They may also have a preference for maintaining a sense of mystery and enigma in their interactions with others.