Today, I will explain to my healthy transplanted heart why, in what may be a matter of days or weeks at best, she – well, we – will die.

I slide my hand across my chest and speak aloud, palm to my heart’s crisp beating. “I’m so sorry, sweet girl.” She is not used to hearing me this way, outside my head, beyond the body we share. Up until now, the understanding between us has been internal. Like on our daily runs, when my 70s yacht rock playlist propels each stride; this heart from a 13-year-old donor revolts in my body with thumps of Oh puh-lease – and we giggle together, picking up our pace to sprinting.