''We really need more doctors,'' manager Jo Rowe said yesterday.
The practice has 512 patients, and is not accepting any new ones at present.
It has one full-time-equivalent GP, comprising seven GP volunteers.
Carrying out more GP clinics would attract more government funding and donations helped.
''From my understanding, I believe that we have about three to four years left of the service before we effectively run out [of funds], if we didn't gain any further support or didn't gain any further doctors.''
The practice had a Christian ethos, ''ideally'' GPs were Christian, but this was not essential, Mrs Rowe said.
She accepted health in New Zealand operated largely as a ''business'', and the practice was not ''politically driven'', she said.
''There's faults with every health process, and every health system, and there will always be people who are unhappy with things that are going on.''
She estimated the centre would have more than 2000 patients if it accepted everyone in need.
''It's very hard, and it breaks our heart,'' she said, of having to tell people the centre could not take them as a patient. The centre referred those it turned away to other organisations.
Patient numbers were frequently reviewed to see if more could be admitted.
The Southern Primary Health Organisation, which distributes the Government's general practice funding, was highly supportive of the centre's work, she said.
Mrs Rowe, whose background is in nursing, worked as a unit manager at the Southern District Health Board before taking on the centre manager role 14 months ago.
It was a ''holistic'' service, both in providing a ''spiritual aspect'', and helping patients improve their lives.
''Seeing change for people is a very fulfilling thing,'' she said.
''I believe that every staff member here is fulfilled by knowing that they are doing everything that they can within their capabilities to help our patient group.''
She felt she had enhanced the holistic nature of the service by starting a weekly coffee group for patients.
The centre's goal was not to convert patients to Christianity, although some went on to attend church after making ''massive changes'' in their lives.
''That's my faith; that's what drives me. It's not what I expect to drive everybody else.''
The centre had four counsellors.
Since it opened in 2010, 235 patients had moved on to other medical practices, indicating they were now able to pay.
Nearly a quarter of patients were Maori, and nearly 23% were aged 15-24.
The number of young patients reflected the high level of youth unemployment, Mrs Rowe said.
