She told Fairfax Media that she wishes she hadn't been "so lazy" in getting checked for breast cancer, especially given that her mother has had it.
Ms Jacenko said she believed breast cancer mostly targeted women over 40. She is just 36.
The Sweaty Betty publicist urged women to "be vigilant with self-examination".
"Don't just happen to be showering and come across a lump like I did," she said.
However, she was upbeat. "I'm good hands with the team at St Vincent's...It can only be up from here... you've got to tackle things head on. I've got two young kids. I have responsibilities. So it's business as usual, just with a few [doctor's] appointments in between."
To find out more about breast cancer screening visit Cancer Screening.