How do I tell my mom I want to be a singer?

Okay, So this is a secret I have been keeping from my mom since I was about 5 years old (I'm currently 15 in high school). I've been in choir for 5 years, I've always known that I wanted to be a singer, But It really hit me about in 6th grade when I was auditioning for my choir class, and my choral teacher asked me if anyone besides me knew that I could sing how I sing because I was a very good singer for being in 6th grade, after that I automatically knew thats what I wanted my career to be. I sing almost everyday(when my mom is not around). But I just don't know how to tell my mom that this is what I want to do...?