I've heard it said that some people "wear their hearts on their sleeves." I often wonder if there are some who wear not only sleeves, but a thick "designed-for-subzero-temperatures parka" over their hearts. 

The  Wizard of Oz muses "Hearts will never be practical until they can be made unbreakable." Undoubtedly, a beating heart keeps us alive, but people do die from a broken heart. How ironic that what keeps us alive in happiness, can also lead to our demise in the absence there of?