Let me tell you about two people I know: "Dave" and "David."
Dave is a charming, fun-loving kind of guy who strives to live life to the fullest. He is a talented singer and actor. He listens to classic rock. At a party, he's usually one of the last to leave. He finds it difficult to settle down and focus on a particular task. He is something of a spiritual mystic, and often attends neopagan rituals.
David is an instrospective, serious-minded individual. He teaches and tutors math. He listens to classical music. Generally shy, he's the sort of person who doesn't get out much. He plays chess and can easily focus on a position for long periods of time. He is religious, and recently became an elder in the Presbyterian Church.
Both Dave and David are, of course, myself. And individually, each of them does pretty well.
The hard part is getting them to communicate with each other.