I also draw the line where 13-year-olds, whose body is still growing, want to have plastic surgery because they don't feel sexy enough yet. Let them grow up first, then they can still decide if bigger lips or boobs are necessary for their self-esteem or self-worth.
As for myself, I've had plastic surgery. I suffered from a terrible inferiority complex because of my nose. I've tried to come to grips with it, told myself that I have to accept who I was. It didn't work. I just felt ugly. It has really changed my life for the better when I finally decided to have the operation. That was about 10 years ago and I still think it was the best investment of my life.