Marissa Rancan, 62, displays her age-defying curves during a workout session with Chad Hurst

Marissa Rancan was a fierce competitor during Big Brother Australia‘s challenges.

And on Saturday, the 62-year-old proved she is determined to keep fit as she endured an intense workout hosted by her former co-star Chad Hurst in Sydney.

The former aerobics queen looked youthful beyond her years as she displayed her well-toned figure in stylish sports gear.  

The fitness enthusiast put on a leggy display in a black shorts and a pink T-shirt.

She teamed up the attire with grey sneakers while wearing her blonde tresses tied back behind her head. 

Marissa, who was once part of the iconic 1980s aerobics group The Rancan Sisters, demonstrated her impressive strength as she pummelled the trainer’s punching pads with gusto, before doing squats. 

During the session, a determined-looking Marissa was seen skillfully pulling off a number of boxing moves, including jabs, upper cuts and cross punches. 

Making sure to work out her entire body, the fitness enthusiast also took some time to perform a set of lunges and hamstring stretches. 

Meanwhile, Chad, 27, was back to work as a personal trainer despite winning a whopping $234,656 on the show this year.  

Chad looked in good spirits as he led a circuit, which consisted of the all-female group doing upper-body exercises. 

At one point of the workout, the hunky model-turned-personal trainer was seen demonstrating moves while the group looked on. 

The model runs a mix of classes and runs PT sessions in Sydney.