Nina Marino, 19, and Joey Williams, 21, hoped to get married on Sept. 4 in the chapel at St. Joseph’s Children Hospital in Tampa, Florida. But their plans changed quickly just one day earlier when doctors told the couple that Marino, who had terminal cancer, wouldn’t make it through the night. “The doctor encouraged us that, if we wanted to be married, we should do it that day,” Williams, of Clearwater, tells PEOPLE. “It was a lot all at once. Nina just said, ‘Okay, let’s do it.’ “ So they did.