About 600 Christchurch Hospital staff are swapping their scrubs for active wear this summer.
The emergency and radiology departments have committed to get exercising for at least 30 minutes a day, for 100 days.
"We're the front line of health so we should be trying to promote a good, healthy existence," emergency physician Dr Jan Bone said.
"That's the idea behind getting people moving and doing some regular exercise."
The EDGE (Emergency Department Gets Exercising) Challenge was put into action by Dr Bone and a team of three others last year.
After seeing the benefits, they're doing it again.
"You can imagine in a department where we've got 300 total amongst all our disciplines, it's really easy not to know lots of them and to feel embarrassed about that," Dr Bone said.
"So we divided the whole department by discipline, mixed them up into 10 teams and the spin-off of the whole thing was people started talking and everyone was nicer to each other."
The teams gain points for intentional physical activity - not the steps on their Fitbits - and can get additional points for being active with team members.
And the benefits of the challenge aren't limited to better fitness.
"What we've found was our team spirit in ED just rocketed.
"We know that our care is better because we're working better together and that's giving our patients a much better outcome."
This year, the 300-strong radiology department have signed on for the summer challenge too - inspired by the success of their colleagues in ED.
"Jan told me about one of their staff members who came up to them after last year's challenge and said I've been working here for five years and only after the challenge did so many people know my name," radiology's charge sonographer Rex De Ryke said.
"They'd felt pretty disempowered in the department until afterwards when they felt part of the team, so I think their enjoyment at work really went up and that's what we're doing it for.
"In radiology, a lot of us work in our own areas.
"We don't actually get to see the other guys from CT, MRI and even AIDS so much, so it's a good way to get to know some different people and a good way to get a bit fitter in summer as well."
The challenge runs until April 18, 2017.