But in all that time she says she has never tackled anything like next month's Gibb River Postie Bike Ride, a charity event organised to raise money for Bright Blue.
The Hamilton Hill resident will join 20 other riders travelling from Kununurra to Derby, taking in the scenery while negotiating creek crossings, unsealed roads and sleeping under the stars.
Mrs Irwin's aim is to raise $5000, with all that going to Bright Blue and its work supporting the prevention and treatment of childhood illnesses.
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READ NOW"It looks really challenging but it's for such a great cause," she said.
"I just thought Id try to raise the money and I signed up."
Mrs Irwin joked her biggest concern was crocodiles.
"We will pass through a number of creeks and rivers along the way," she said.
Mrs Irwin, based at Australia Post's delivery centre in Palmyra, delivers to North Fremantle.
She said the response from people and businesses in the area had been incredible.
As of last week, she had passed the $3000 mark.
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