And boy, what a large membership. The majority of the 2100 women are based in Whangarei, but the fitness movement has spread across the region and even across the water, Austin said.
"I guess, yeah, it is more of a movement now."
In fact it is all about movement.
"It's about fitting in little bits of helpful movement and activity - any movement, not just exercise," she said.
"The word 'exercise' scares people."
Austin said her members were the backbone of the forum."
She said friendships had formed from the forum too and many women found the social aspect as supportive and energising as the activities.
For now, Fit M In is a movement for women, but "men are asking about when a men's group will start".
"We will have to see."
Austin has been working in the fitness industry since 2001, and in her own fitness business (originally One2One Fitness but rebranded as Fit Fix last year) since 2007.
She also writes a fortnightly fitness and health column called No Excuses for the Northern Advocate. She holds a Bachelor of Sport and Exercise Science and a Postgrad Diploma in Psychology - having studied at Waikato Institute of Technology and Massey University - as well as a range of industry qualifications. She is also the Northland ambassador for the Personal Trainers Council of NZ.