How do you tell your parents you want to join the Army and make it a career?

I want to join through the ROTC program when I turn 18 so I will be commissioned as an officer when I'm 22, then I want to rise up through the ranks and be promoted to a higher ranking job like major. I'm only 15 but I've already began getting ready for the ROTC program because I have good grades (85 Average), I am taking honors classes next year as a sophomore , I have no conduct issues, I am on my schools track team, next year I'm going to join karate and wrestling, and I do community service as well as help with school activities.