Grades as a Discourager

I know that I work better when I do not have the pressure of grades pushing down on me.  I am told by almost all of my professors that grades do not matter, and I completely understand that they don't. However, my parents do not see it the same way.  I feel as though anyone outside of students and faculty in art school do not understand this mindset.  I am unable to be as creative under pressure as I would be making art on my own.  This is why I enjoy painting and making things so much during my free time.  My work is much more creative and free this way.  I need to find a way to psychologically trick myself into this mindset for all aspects of my work.  At this point, I am unsure what to do other than to simply ignore the grades.