My great grandfather who died in 2008 was simply eating breakfast at the nursing home he was at (he was still rather mobile, I don't know why he was in a home). He ate a biscuit with sausage iirc, breathed deep, and simply keeled over. My family says he died of a broken heart, which isn't far from the truth. He had watched his wife of 50+ years lose all her memory and motor functions and forget who he even was over the course of just a couple years. She died after him though.