Viewers saw the Olympian deal with the family tragedy on screen, but now she's opening up more about her grandmother's struggle with Alzheimers, as she partners with the Alzheimer's Association for Alzheimer's & Brain Awareness Month to help bring attention to the disease that affects an estimated 5.5 million Americans.
"[My grandmother] started getting sick in mid-2016... We'd hoped she would get better soon, but we did see her spiral downward throughout the year. She had stomach cancer as well as Alzheimer's and the two hit pretty quickly," Hernandez said in an interview with CBS News on Thursday.
"Through the Olympics, I could feel that she was watching, and when I came back, the people who had worked with her created a little book for her of all the meets that I did with pictures and descriptions -- that way she could go through it," she remembered. "That was really comforting to know that she saw what I did and that she was hopefully proud of it."
Hernandez said that things got really bad when she started on DWTS.
"When I did find out, I got to fly home for the week... I didn't cry at first. I don't think it hit me, really, just because I had been traveling so much I'd gotten used to not seeing her as much. So when they told me, I was in shock, I guess. And then a few days later, it hit me and of course it hit when the cameras were on, so that was definitely really hard," she recalled. "But everyone at Dancing With the Stars, the producers and cast and everybody were really sweet. They had written a card sending all their prayers and there was a lot of support from everyone, so that made it a lot better."
The DWTS champ, who remembers her grandmother as a "firecracker" with a "tough heart," hopes others with family members suffering from Alzheimers "spend a lot of time with them."
"Take in every moment, because you never know when something can happen," Hernandez said. "You don't want to have any regrets at the end."