"The beach is covered with people exercising early in the morning, before a lot of people get up - there are lot of people exercising in Auckland."
But Auckland also had a large population and exercise rates varied between suburbs, with lower socio-economic areas typically having higher rates of diabetes and obesity.
Mr Richards said Dunedin's higher exercise rate was possibly due to its large student population.
"They haven't got much else to do apart from go to university and go to the gym and socialise."
Mr Richards was surprised by the percentage of people who said they exercised four times a week or more. He said only 12 per cent of New Zealanders were members of health clubs.
"It's so hard to get people to exercise because so many are a bit lazy."
He said people might be motivated to go to the gym for two to three weeks at first, but it required a lot of discipline to keep it up long-term.
Tom Davie, head trainer at Dunedin gym Body Synergy, said a typical client would exercise about three to four times a week.
"Possibly Dunedin's got more accessibility to parks and things like that. It's a lot smaller than Auckland, that's for sure."
He said winter was the busiest time of the year.
The survey found people under the age of 30 and over the age of 50 were most likely to exercise. People with children were the least likely to exercise regularly.
Of those who exercised regularly, 46 per cent said they had lost weight as a result.
Fifty-five per cent said improved health was their motivation for exercise, while 40 per cent cited weight loss, 34 per cent said they enjoyed exercising and 20 per cent wanted to improve their appearance.
The online survey of 2006 people, conducted in late August and early September last year, had a margin of error of +/- 2.2 per cent.
It was weighted to be representative of New Zealand's over-15 population by age, gender and region.