Quote: I try to carry the conversations when he's not very talkative - but I'm not so sure he is interested in what I'm talking about.
Make the conversations about him. People love talking about themselves. A good way to do this is to follow everything he says by turning it into a question, to keep him talking. Like this:
H: Rough day at work today! You: You had a rough day? H: Yeah, Smith almost blew the company's biggest account. You: He almost blew the biggest account? H: Yeah, what an idiot. I managed to stop it before it was too late. You: You stopped it?