The difference between the two is in the way they express the disagreement of opinion or circumstance. The small heart will act with anger while the big heart will respond with understanding.
How I be a big heart one?
I try to see circumstance or opinion in many perspectives, as many as I could. Then, every time I get piss with them, I have two options: I can give them fuel for anger or I can remain silent.
If I want fire, I will make it.
Or the other way around.
And life is a matter of choice.