What is it to “have heart”?
It is the passion, the faith, and even the stubbornness to stay in the game even once it seems certain that all is lost. It is the resolute refusal to ever quit or give up, regardless how grim the outlook or how certain the defeat. It is to believe beyond all hope or reason for a turning of the tide ~ what J.R.R. Tolkien called a “eucatastrophe,” a “sudden happy turn in a story which pierces you with a joy that brings tears.” (He believed there ought to be a word equal in strength to catastrophe, but opposite in effect. So he coined one. Gotta love that guy.)
To have heart, then, is to never stop hoping for the eucatastrophe to come, and even if it does not, to rip and tear at the darkness until the very last drop of blood drains from your body.