[The question seems to take him by surprise, as if it's completely out of left field for him.]

I...

[And in fact, it is. Not once in living memory can he recall anyone ever asking him what his hobbies were. Being a magician and the work that entailed was something all consuming to him, and it was plain to those around him. They expected no less..]

My job is my hobby, of course. Though, to be quite honest... a hobby in the traditional sense of the word that you mean... is really only something for people with time to waste.