It's true, Jack Pinsky had six hearts. 

It's true, Jack Pinsky had six hearts.  He had of course been born with just one but as he grew older and took on the many responsibilities that come with age, he found he needed a separate heart for each separate aspect of his life.  He had: 1. a heart to love his wife with.  2. a heart to love his kids with.  3. a heart to take risks with strangers with.  4. a heart to use at work (he was a contractor).  5. a heart to blame all his shame and disappointments on, and  6. a heart used to store all his loneliness.

Jack lived in constant fear of a heart attack.  It wasn't dying itself he feared.  It wasn't leaving his wife and kids behind.  It wasn't any of that. He simply feared dying without knowing which of his six hearts had finally failed him.