A few years back I realized how futile my attempts at being a super-woman were. I never tried to dodge bullets or jump from the roof and fly (even thought flying would have been a practical super-power to have...). But I did try to be mentally & emotionally indestructible.
How does the heart relate to mindfulness? Mindfulness is about being present to what you're feeling, thinking and sensing. Connecting to our hearts enables us to be in "the heart of the moment," and if you don't want to get hooked into those thoughts and feelings, you let them pass through.