Extroverts, those outgoing, gregarious types who wear their personalities on their sleeve, are generally happier, studies show. Some research also has found that introverts, who are more withdrawn in nature, will feel a greater sense of happiness if they act extroverted.

Experts aren't entirely sure why behaving like an extrovert makes people feel better. One theory is that being talkative and engaging influences how people respond to you, especially if that response is positive. Others speculate that people get more satisfaction...