How to find my greatness?

So my mom said to me last night "Find your greatness" and I'm sort of guarded, I hate my body, I um don't eat as much as i use to. I eat only like 150 to 300 calories a day, i'm always dissing myself, And every time i look in the mirror i think ( Ugh, I hate you, Is that me? An ugly girl staring at me? ) I have low self confidence and i'm constantly trying to change, What does she mean by "Find your greatness" ? My sister and my mom are fearless, I'm not, My mom says to chase my dreams but my shyness gets in the way of what i want to do. like (Gymnastics, Ballroom dancing, Singing, ETC.) Thanks!