A combination of grief and unhealthy lifestyle choices had caused the Emerald resident's weight to balloon to 115 kilograms and to plummet her into what she describes as "a black hole".

It started five years ago when she had to deal with the deaths of her 13-year-old niece, her father and her best friend all within a year.

"I thought I was coping but when I look back I wasn't," she said. "I've always been a strong-minded person but I began to drink, eat, and smoke more to cope."

The turning point came when Ms Hoffmann's eight-year-old daughter Jorja took a photo of her sitting outside with a cigarette dangling from her hand. She barely recognised herself.

Ms Hoffmann made a promise to herself to change her life. Last year, she began the Michelle Bridges 12-week body program and began personal training with renowned martial arts and boxing expert Tommy Hopkins. Since then, she has lost almost 40 kilograms.

In April, to mark what would have been her niece Stacey's 18th birthday, Ms Hoffmann is undertaking a fitness challenge to raise money for the Heartkids foundation, which supported her niece during her battle with cardiomyopathy.

Ms Hoffmann will be completing a thousand burpees - a cross between a jumping jack and a push-up - in an hour.

Hoffy's Burpee Challenge is on at 11am on Saturday, April 14 at the Ferntree Gully Hotel. Details and donations: Click here or call Julie Hoffmann on 0488191119.