What started as a favour has resulted in more than 200 people signing up with the Rotorua Group Challenge to lose weight and get fit.
The 12-week challenge is run by David Massey, who says he wants to "pay it forward" after being given the gift of health and fitness himself.
It started out last year when a friend asked him to train a group of mums who wanted to lose weight and train together.
"I took one session and they kept asking me to come back," he said. "There were eight in that first group challenge in March last year and it's just grown since. When we got to 45 I thought that was huge but we just finished the last one where 161 registered and now 200 have registered for this next round."
All entrants pay $20 to register and the money is pooled together as a prize for the person with the highest weight loss by percentage. That was won last time by Donna Dunkley, who lost 11.8kg in 12 weeks and started running in the process.