Introversion is the state of being predominantly interested in one's own mental self. Introverts are typically perceived as more reserved or reflective. Some popular psychologists have characterized introverts as people whose energy tends to expand through reflection and dwindle during interaction.
From Wikipedia:
Susan Cain
I prefer listening to talking, reading to socializing, and cozy chats to group settings. I like to think before I speak (softly). Until a few years ago, I was terrified of public speaking, and I am still amazed that such a giant fear is conquerable. During the last few years, I’ve given hundreds of talks, a fun fact that would have astonished my childhood—even my 40-year-old—self.
Website: Quiet Revolution
Podcast: Quiet: The Power of Introverts
Gretchen Rubin
OK, so technically she identifies as an extrovert, but belongs here because she is an Upholder, a person who responds to both internal and external expectations. Gretchen graduated from Yale Law School where she served as Editor-in-Chief of Yale Law Journal. She went on to clerk for Sandra Day O'Connor at the United States Supreme Court. She left the law when she realized that she really wanted to be a writer. Gretchen describes herself as an Upholder, one of the Four Tendencies--a framework that she devised to describe personality styles relating to habits.
Website: Experiments in the pursuit of happiness and good habits
Podcast: Happier