Shirley Potter’s holiday is the opposite of how most people enjoy a break from work.

Instead of lounging by a pool, Peter Mac’s Plastic and Reconstructive Surgery Fellow will be slogging through desert sand in temperatures up to 40 degrees. Shirley will compete in the Sahara Desert Race, a gruelling 250km footrace that will take in some of the world’s largest sand dunes.

The six-day race starts on May 1 and is held on Namibia’s Skeleton Coast.

“The other thing about it you have to carry all of your supplies, so I’ll be carrying about 10kgs on my back,” she says.

“But I can’t wait - the last one I did was probably the best thing I’ve ever done so I thought `why not do it again?’.”

Shirley ran in a similar 250km race in the Gobi Desert and said it felt amazing to finish knowing she had tested herself to the absolute limit. In this race in the Sahara, she will run a marathon daily for four days, then a 77 km Day 5 and finally a “fun run” 10km on Day 6 to the finish line.

“They say that life begins at the edge of your comfort zone. That’s how I would describe it,” Shirley says.

She has a fundraising website for people to show support – and 100 per cent of monies raised goes to the Peter MacCallum Cancer Foundation to fund cancer research.

“I work here and see all of the good work that Peter Mac does and all the research that Peter Mac does – so that was an easy decision,” she says.

Shirley got on a plane bound for Namibia on Thursday.