Commuters from Wellington come to the studio "straight from the train" after work.
Originally from a "very corporate" background, Ms Penlington decided about 10 years ago that she enjoyed pilates so much that she would start teaching it.
One thing led to another and about three years ago she started Gain Momentum.
According to Ms Penlington the point of difference for her business is that she and her eight staff focus on both the body and the mind.
She gave the example of a stroke patient.
"The stroke happens and affects the body physically but the person can't actually see it. It's just so frustrating, they are telling the right leg to move but it just won't.
"Frustration leads to anger and depression. Depression is a big part of it - so you work with the physical body and the person inside."
Ms Penlington has many examples of success stories where people have recovered through the techniques Gain Momentum teaches them.
"We've got people out of wheelchairs, got people back to independent living - cooking and feeding and bathing themselves."
Ms Penlington said her business caters for people of all ages and abilities - from recovery to serious strength work.
"My youngest client is 9 and my oldest is 85."
She says Gain Momentum already has 300 members and is growing - along with Carterton in general.
With the only osteopath in Wairarapa, pilates, yoga and massage specialists, Ms Penlington says Gain Momentum can cater for most and encourages anyone to join in on daily sessions.