Flex Fitness Rotorua manager Nic Haldezos said they had noticed there were issues in the community directly affecting their members.
He said they realised the gym could do something to help and hatched the plan to give members a say in charities they could get behind.
Last month the gym got close to 80 new members and it was tracking for a similar number this month.
When selecting this month's charity, Haldezos said he was made aware there were members who were either related to, had lost or were "at-risk youth".
"It's important to donate to a place that could provide support systems for these adolescents."
The gym already had close to $2000 to donate to the not-for-profit organisation.
Gyms across the country had a responsibility to advocate for both their members' mental and physical health, he said.
"If we can give back to their fitness, why can't we help them in other aspects of their lives too?"
Rotorua Youth Centre youth development manager Steve Holmes said their service was all about young people's mental and physical health and every dollar helped the centre make a difference.
He felt there was a community need to address and prevent youth suicide.
The youth centre helps hundreds of adolescents across the city with a range of programmes, activities and counsellors they could refer at-risk youth too.
He said developing programmes to allow youth to have a "bright future" was everything.
The centre was currently working on an employment support programme, involving 1400 Rotorua adolescents and 83 employers.
It aimed to set them up to put their "best foot forward" and give them purpose and drive, which had immense mental benefits, he said.
He said programmes like this were pivotal in helping youth remain "positive".
The gym's plan was to let members decide a new local charity every month through social media and a suggestion box at the door.