Counter was rushed to hospital, where she remained in a coma for three days and needed open-heart surgery.
After further tests, Counter was diagnosed with Bland-White-Garland Syndrome (BWGS), a rare form of heart disease which, if untreated, can be fatal.
"I'm one in 300,000. Most don't survive past infancy if they've got this condition," she told 7 News.
After making a remarkable recovery, the Sunshine Coast local told the Courier Mail she initially thought the pain she felt in the gym was just down to her being unfit.
"I was getting heart pain and I was struggling breathing when I was running, way before I had this happen, and I thought I just wasn't fit enough."
More than four months on the young woman can now start exercising again and now wants to get defibrillators in every gym.
She says if it wasn't for the defibrillator in the gym that day she wouldn't be alive.