Pregnant with her second child, Pitt prepared to join the convoy of evacuees clogging up the roads out of Ulladulla as fires threatened the NSW south coast earlier this month.

The fires on New Years' Eve which destroyed 382 houses in the region triggered a recurring nightmare of running through the flames with her son.

She told her nearly 900,000 Instagram followers she was trying not to let the "panic genie out of the bottle".

"It's been difficult to sleep, eat or think and all I've really wanted to do is tap out, put my head in the sand and pretend that nothing is going on," she wrote.

Pitt is renowned for surviving a 2011 grass fire after she was cornered in the blaze along with other runners while competing in a 100km run in Western Australia's Kimberley region.

Suffering burns to more than 65 per cent of her body, the then-24-year-old was left with no fingers or thumb on her right hand and a long road to recovery.

Doctors told her she would never walk again.

"I didn't focus on the enormity of the task that lay in front of me," she told AAP on Tuesday.

"If I managed to do just one thing that day I would congratulate myself on a job well done."

When asked if she had any advice for recent bushfire victims Pitt demurred.

"I don't give advice," the motivational speaker said, "I just speak from experience."

That experience included more than 200 operations and six months in hospital.

Pitt says setting small goals helped her get through.

"We can all relate to that, whether it's a career goal or training for a marathon it's easy to get overwhelmed," Pitt said.

"As the saying goes, how do you eat an elephant? Bite by bite."

Seven years after being choppered out of the desert, Pitt faced the flames again.

Her family, including fiance Michael Hoskin and two-year-old son Hakavai, were not forced to evacuate their Ulladulla property, remaining safe from the blaze.

But Pitt was furious when friends talked of staying to defend their homes.

"You have no idea that a fire sounds like a thousand road trains coming towards you," she posted on Facebook.

"You have no idea how hot it feels and that you will watch your skin bubble before your very eyes."

She dismisses platitudes about her bravery, preferring to talk up her initiative to support bushfire-affected small businesses.

Inspired by the Buy from the Bush campaign, @spendwiththem leverages Pitt's large social media following to connect retailers with potential buyers and promote their products.

In its first 24 hours the account gained more than 60,000 followers.

"Now is going to be a pretty frightening time for small businesses. Having people know about them and support them makes all the difference," Pitt said.

As a small-business owner she wanted to help others struggling to recover.

"I have an amazing life, friends and family," she said.

"Once you stack up your life against anyone else's - it's just the right thing to do."

Australian Associated Press