oxygen!

"When we turn away from someone, or offend someone, then it is as though a stone were placed inside our heart."

It is.

And I don't want a heart full of stones ever again.

Like a sack full of stones I would sink to the bottom of the ocean.

Like a sack full of stones I would drown. 

I would suffocate.

I need to pray like I need to breathe, for God is the breath of life.

And a heart full of stones would drown me.

Let me explain: we need kindness in our hearts in order to breathe.