And with a swag of gold medals and world records under her belt, that is a hard to imagine.

The swimmer was on hand at the Nulkaba school on Friday when the new Activate Centre was officially opened.

She said she was "blown away" by the complex, which includes a gym that would rival a commercial set-up, a basketball court that converts into an 1100 seat auditorium and four classrooms upstairs.

"You guys have got a once in a lifetime opportunity," she said addressing the crowd. "Take every opportunity you can to use these facilities because they're amazing."

Principal Darren Cox said every student from years 5 to 10 took part in three gym sessions a week in the new centre and senior students and staff were allowed to use the gym before and after school and during lunch times.

"The kids are just thriving using the space," he said. "Fitness lessons are now their favourite lessons."

Mr Cox said as well as being something the kids enjoyed, the new centre would also help improve their health and wellbeing.

"The statistics around young people's health are at an all time low," he said. "That links to mental health too.

"This is an innovative way to do something about that. [We hope it is] a vehicle to establish lifelong habits."

The project, worth roughly $8 million, was first conceived about four years ago and involved $1.2 million in grant funding.

St Philip's Christian College executive principal Graeme Irwin said the school had another project on the drawing board - a two-story senior school building, which they hope to start construction on next year.

The school also hopes to establish its own early learning centre after that.

But for now, Mr Cox is happy with how the school will be perceived with the latest project.

"We used to be known as the school with the slide, now we're the school with the gym," he said.