The answer used to be so simple: your children, of course. But times are changing and for many families, that option seems impossible.
Polls show the vast majority of baby boomers expect that when the time comes, their kids will take care of them. But the same polls also show those kids don't think that's a sacrifice they can make.
WellMed, a local medical organization, is empowering people to become caregivers by offering free local classes that can bridge that gap.
Rebeca Cardenas says her mother lived alone on San Antonio's west side well into her eighties.
"She was a brilliant person," Cardenas says. "The type of person you'd say, 'She's not going to get Alzheimer's or anything.'"
But about four years ago the warning signs appeared, and it was scary.
"She was getting lost," Cardenas says. "She would go out, driving her car, and get lost."
Cardenas lived in Mexico City so she moved her mother there to be with family. But this past February, it became obvious her mother was not going to make it and needed medical care in San Antonio.
"It was no time for her to be living alone anymore," Cardenas says.
So she made the difficult choice to drop her life in Mexico and become her mother's caregiver.
"They give us so much. My mom loved me so much," Cardenas says. "How could I not give her back what she gave me for so many years?"
But she's the first to admit she felt isolated from her old life. It's grueling work, especially if you don't have a medical background.
"The stress is just very bad," Cardenas says. "It's like riding a roller coaster. Some days are just heartbreaking."
The obstacles she faced are quite common. Families are scattered and are much smaller than they used to be.
"If there's only one or two children, and you have children to take care of and other demands, and now we've got both of the people in the marriage are working - there's not anybody staying behind," Carol Zernial from WellMed says.
That's why WellMed has Caregiver S.O.S. resource centers offering free classes to people caring for an older family member.
"Not only do they have stress-busting, they have chronic disease management, falls prevention, they've got techniques to help caregivers feel like they have solid ground under their feet," Zernial says.
Cardenas says the classes taught her to cope with stress. She also met other caregivers hwo could relate to how difficult it is to care for someone who is dying.
"Through those nine weeks, I changed totally," Cardenas says. "At the end I was enjoying, really enjoying, taking care of my mom."
The end came just two weeks ago. Cardenas was by her mother's side when she died.
"I don't have any regrets," Cardenas says. "I feel at peace."
It's a peace of mind, knowing she cared for her mother until the very end.
Cardenas hopes she's setting an example for her son so he'll make the same sacrifices to take care of her.