Why do you need to justify yourself? I have heard that in Europe asking people what they do for a job is considered to be very impolite. You could always say that you are independently wealthy and don't need a job. The other thing is to get in first with that question and then follow up with more questions. Some people do really like to talk about themselves.

Another question you could ask people is "What do you fill your week in with? Or if you are at some social gathering find a plate of food and offer it around. Kind gets you out of that sticky situation.