How do I tell my parents that I don't want to be a lawyer?

Ok so since like Grade 10 my parents have been ON MY CASE about what I want to do with my life and my career. I had no idea what I wanted to do, which I felt was completely valid considering I was just a high school kid. By Grade 12, I really wanted to just get them off my back so I just told them I want to be a lawyer (keep in mind I have zero interest in law). My parents are one of those parents who think the only good jobs that exist are doctor, lawyer, or engineer so you can imagine they were pretty pleased. We agreed that I would do an undergraduate degree in psychology at Waterloo and then go to law school once I graduate.

I'm entering my 3rd year soon. Honestly I'm still not sure what I want to do once I graduate, but I know that I definitely DO NOT want to be a lawyer. My parents still think I'm their future lawyer son and I am kind of nervous about how I should break the news to them.

Thoughts/advice?

P.S. Keep in mind that my parents are Nigerian. They are not understanding. They are not sympathetic. They are not open-minded. They are, however, very controlling.