Michelle Pittman and then nine-year-old Dylan Deane saw a sign for Mount Royal National Park near their Hunterview home on the October long weekend in 2017.

The mother-and-son set off to enjoy the outdoors and have a little look around.

They hadn't been planning on going for a bushwalk, but found a track and decided to follow it, before coming to a rocky river bed.

"And then when we crossed over that, we never actually found our way back," Ms Pittman said.

It set off a chain of events that saw them spend 10 days cold and starving in the national park, drawing on skills picked up from watching Bear Grylls on television, sucking condensation from plants for a lick of hydration.

"It was very scary," Ms Pittman told the Newcastle Herald.

"But it wasn't until about the afternoon on the second day that I realised we were in deep trouble.

"It was just all about survival."

Dylan, just nine at the time, asked his mother if they would still be lost in the bush at Christmas time. Ms Pittman said she knew what it meant if they were, but she couldn't give up.

"It was just that mindset that I made a promise to myself that I would get him out at any cost," she said.

They spotted a rescue helicopter one day, but had no idea emergency services had launched a large-scale search in a desperate bid to find them as time ticked on.

They trekked up high to try and escape the rainforest that shielded them from above, then low in search of water.

Ms Pittman's phone went flat on the first night but she used her car keys to set off her four-wheel-drive's alarm in the hope she might be able to hear it.

Without any supplies, equipment or experience, Ms Pittman said they relied on love, instinct and grit until their rescue.

"We walked out on the 11^th day," Ms Pittman said.

The mother and son spent time in hospital but physically recovered well.

They were no longer lost in the national park, but there were times for years afterwards where Ms Pittman felt even more lost in real life, as the mental pain lingered.

"Even though we were only in there for 10 days, it seemed like were were alone for months and years," she said.

"I felt really guilty, believing that it was my fault.

"It was a long recovery."

Ms Pittman has now penned a book - titled LOST! - inviting readers on the true story of their harrowing experience in the vast expanse of Mount Royal National Park, near Singleton.

She said she hoped it would be something she, Dylan, her other children, and anyone else that picked it up could refer to if they felt hopeless or doubted themselves.

LOST! is available directly from Ms Pittman, on Amazon as an e-book or paperback, and from select bookstores.