"We have lost weight and are way fitter now, we have gone from not being able to run for more than 20 seconds without getting puffed to training for a marathon."
Mrs Raymond said they originally joined because they were "getting old" - both were in their 50s - and they wanted to do something together.
"It's definitely brought us closer together because we run together every night."
Mrs Raymond said before they joined the group they would just sit on the couch eating chips.
"It's amazing, it's changed our lives," she said.
Fellow group member Maseilles Driver, 34, will also be running the half marathon.
Ms Driver is a mother of five who joined Rotorua Group Challenge in April and has since lost 16.9kg.
"Running is my quiet time. I wasn't happy with my weight and one of my customers passed away from a heart attack, that gave me a kick-start."
Ms Driver said she had run 18km before in training.
"I hate [running] while I'm doing it but afterward I get such a sense of accomplishment."
The events start and finish at the Village Green. Enter at runningfestival.co.nz.
