After completing Tough Mudder, City2Surf and the Coastal Classic, the members of team Eager Beavers 4 were looking for a new challenge.
When their group fitness trainer suggested the Sydney Coastrek, it sounded like the perfect way to test their limits.
Danielle Pike, Sharyn Briard, Nadine Egan-Scott and Peta Wanstall make up Eager Beavers 4, one of four "Eager Beaver" teams from the Illawarra taking part in the 100-kilometre charity walk.
The Sydney Coastrek, which raises money for The Fred Hollows Foundation, begins at Palm Beach at dawn on Friday, with participants following the coastline to end up at Coogee Beach the next day, meaning they walk through the night.
"We're all mums, so we've been through the sleepless nights before, so we've got the stamina from when our children were young," joked Ms Pike.
"A lot of caffeine and camaraderie will get us through."
In preparation for the long trek, Ms Pike said the women had been adding a few extra walks to their usual group fitness sessions.
"We've been following south from Thirroul Beach down to Bellambi and Towradgi and north up towards Stanwell Park."
While they will take water and a few high-energy snacks with them, several of their hubbies will meet the ladies at various course checkpoints to provide meals and treats.
Eager Beavers 4 are hoping to raise $3000 for the foundation by Friday.
Almost 3000 people are taking part in the event this weekend.
To sponsor the Eager Beavers 4, click here.