But when the 24-year-old paediatric nurse and her 29-year-old partner Mitch Raven bought their home in Nowra, she started giving the idea of fostering more serious thought.

"It's only a two-bedroom house but I kept looking at the second room and thinking, we could use that to help a child," she said.

Over the past 12 months, the young couple have been providing respite care for an 11-year-old girl on a fortnightly basis with the aim of bringing happiness to her childhood.

"We have made it our mission to provide as many fun, positive childhood memories for her as possible," Ms Grady said.

"Being a pre-teenage child, there are not a lot of years left where you can establish these really strong, positive childhood memories so you can look back and remember that being a kid is fun."

Activities include everything from beach days, tubing down the Shoalhaven River, horse riding and a trip to Sydney to visit Luna Park.

"It's not just about the big things, though," Ms Grady said. "You can never underestimate the value of the little and seemingly ordinary things like just reading a book before bedtime or doing homework. It's those ordinary things which make an extraordinary difference.

"Doing regular things and keeping it consistent helps them thrive because I guess in their life they haven't had a whole lot of consistency."

Ms Grady admits her friends and family were surprised by her determination to become a foster carer.

"They were shocked because it's not something most people in their early 20s do," she said. "People thought we just wanted our own kids but that was the furthest thing from our minds."

They have started a photo album for the child in their care, full of happy snaps of their adventures. They send letters to her between fortnightly visits and have started a vision board to give her dreams to aspire to.

"Know that life is tough but you are tougher," she wrote in one note. "You are inspiring, you are beautiful, you are loved."

The couple underwent a 12-month process of screening and training before becoming approved respite carers with the agency, CareSouth.

"I became a foster carer to help young people but I have got so much more from it," she said. "There are challenges but the rewards are so much bigger."

There are about 20,000 children in out-of-home care in NSW and a chronic shortage of carers.

The Association of Children's Welfare Agencies estimates an extra 660 foster carers are needed in NSW over the next 12 months to meet demand.

With Foster Care Week starting on Sunday the peak body is urging more people to consider providing a stable home for children who are unable to live with their parents.

ACWA chief executive Andrew McCallum said foster care takes many forms including respite care, short-term emergency care or a full-time commitment.

"The renewed focus on permanency means that the type of commitment needed from foster carers is changing," he said.

"We need to attract people with a strong desire to support children to return home to their birth families, as well as those who wish to take the more permanent step towards open adoption or guardianship."