It's pretty common, I guess, that when they finally make you quit doing what you are passionate about, you don't have as much to live for. You either have to come up with something to replace it in your life (travel with your wife, TV commentary or whatever) or else you will be ready for the hereafter. In Joe's case, of course, he had a bad cancer, and no way to know at this point whether he could have lasted longer or whether it was just the cancer. No matter what, an amazingly swift and terrible end to what had been a legendary career. It could be a Greek tragedy.
Dang, wiki says he lasted a month, had a heart attack.