It helps knowing someone else understands:

How can I let the introvert in my life know that I support him and respect his choice?

First, recognize that it's not a choice. It's not a lifestyle. It's an orientation.

Second, when you see an introvert lost in thought, don't say "What's the matter?" or "Are you all right?"

Third, don't say anything else, either.

Link Via: Crescat Sententia