STONE MOUNTAIN, Georgia (CNN) -- Rosa Foster sat down at the kitchen table with a plate of fried chicken and a salad. Before taking a bite of food, she bowed her head and prompted her grandchildren to say the blessing.
Rosa Foster is a single parent raising four grandchildren under age 19.
Foster, 54, of Stone Mountain, Georgia, doesn't just see the kids on weekends and holidays. They live with her full time.
Foster is one of 2.5 million grandparents around the United States who are the primary caregivers for their grandchildren.
In Foster's case, she's a single parent, raising four grandkids under age 19. "It has not been a picnic all the time," Foster said. "It's been hard."
Hard may be an understatement, according to Nadine Kaslow, chief psychologist for Grady Health System in Atlanta, Georgia.
"There are many challenges for grandparents taking on grandchildren," Kaslow said. "Many grandparents are older when they take on grandchildren, so you may not have the energy you had as a parent in your 20s and 30s to be running around after toddlers."
Foster didn't have a choice. She said she was awarded custody of her daughter's 2-year old son, Rakim, in 1991.
That was 17 years ago. She's since taken in his twin sisters, Rosea and Ronea, now 17, and 12-year-old Raquel.
"Some days I became a little sad and depressed and I would cry through baby feedings, but I still knew I had to keep the babies together. They didn't have anybody else," Foster recalled.
The unexpected demands of caring for grandchildren full time may have health consequences, Kaslow said.
"You often see people having aches and pains or headaches or stomach aches," she said. "It can be associated with more serious physical problems like elevated blood pressure or things that put you at risk for heart disease or stroke." Health Minute: More on grandparent stress »
Foster remembered sleeping only one or two hours a night while she worked two jobs trying to pay the bills.
Kaslow said it is common for grandparents to feel the stress of financial demands when they're a parent the second time around.
"Oftentimes you're at a place in your life where you're ready to take care of yourself, have more fun, plan for your own retirement," Kaslow noted. "Monies you were trying to save for your own future, you are now having to spend on your grandchildren."
She suggested that grandparents set priorities when it comes to their own career and work. While resources may be limited, she recommended trying to find financial help from state agencies, religious groups or other relatives.
For those who may feel overwhelmed, she added, "You don't need to be the sole caregiver. It's really important for you to reach out to other people in your support network, your immediate family, to get their assistance."
She also stressed the need for grandparents to take good care of themselves. Find time to exercise and eat a healthy diet.
"I recommend if you can, get someone to baby-sit the kids once a week or every other week," she said. "You really need time alone."
Does Foster ever get time for herself?
She chuckled, explaining that she has put her own life on hold for 17 years. But, she added, "I wouldn't have it any other way."
Foster has some serious advice for other grandparents who may be in a similar position: "Make sure you're up for the challenge, because if you're not, you're going to break some kids' hearts. If those kids are torn up a second time, they're really going to be destroyed."
All About Parenting