"It's old and new members."
Many people were keen to come back after splurging over Christmas, he said.
Setting realistic health and fitness goals would help people maintain their workouts, Mr Burns said.
Regular assessments to track progress also played an important role.
"If we reassess them and they can see a little bit of progress - it seems to charge them up again."
Meanwhile, Mr Wilson is warning resolution-makers that sweeping goals, made in a post-party haze, are likely to fail once people return to everyday work.
"A lot of our behaviour is controlled by the environment [and] many of the things we think of as habitual happen in particular situations."
For example, many people found it easier to quit smoking when on holiday because the "usual environmental cues" weren't there.
But once home and back into their old routines, they often started again, he said.
He advised smokers wanting to kick the habit to identify what triggered them to smoke.
Whether it was stress, or a certain activity - for example lighting up after work - people would have a better chance of succeeding if they found something else to distract them from the desire to smoke.
So when you were setting goals or drafting ambitious New Year's resolutions, it was important to plan for "slip-ups" and other problematic situations, Mr Wilson said.
And here's another tip. Rather than honing in on a single overarching goal, set a complementary resolution that will help you achieve that goal.
For instance, taking up an art class or going to the gym after work will distract someone who takes to smoking or eating unhealthy food at the end of their working day.
Goals have to be reasonable and achievable, Mr Wilson warns.
"Breaking a goal into stages is good because it means, first, you know what you need to do and secondly, that failing at one small step doesn't necessarily mean going all the way back to the start." That way if someone slips up, they can go back a step, rather than failing entirely.
Mr Wilson also warned against being too generous with rewards.
"Some people are better able to stick to goals than others - it's related to the personality characteristic of conscientiousness.
"The more conscientious you are, the more likely you are able to make goals and stick to them," he said. APNZ
Successful goal-setting
1. Set a timeframe.
2. Make sure they are achievable.
3. Separate out into small tasks.
3. Review regularly and track progress.
4. Have a reasonable rewards system.
