A perfect shape of heart

I can sing, a perfect shape of heart.
I can paint, a perfect shape of heart.

I can dance, with my perfect shape of heart.
I can laugh, using my perfect shape of heart.

I can make you a cookie, with a perfect shape of heart.
I can knit you a pillow of a perfect shape of heart.

I can do all and beyond these with my perfect shape of heart.
But when you break, you break my perfect shape of heart.