Heart matters

There are many sayings about the heart, like: from my heart, with all my heart, heartbreaking, big heart, small heart. Having this chat today with a dear friend suddenly these heart matters came up. When do you have a big heart and when do you have a small heart? We didn´t get to agree so we looked it up on the internet. I guess most of you already know that having a small heart only means that you feel for other's people harm and that you are not very brave. A big heart means that you always help other people, no matter what, you just do so because you feel that you have to.
I think I have both, a big heart because I believe that you should help people when you get the chance and a small heart because I do feel for other people’s sorrow and I might not always be very brave. Does that mean that there is room for two hearts in one ? Maybe one can have a small big heart.