When he was returning from a working trip in Te Anau last month, he listened to a podcast of a Ukraine journalist who stayed behind in Kharkiv.
"It was so compelling ... They talked about refugees leaving the country by foot and I thought we had all those beautiful walks in Southland. I thought this was something I could do," he said.
Mr Lewis set up a gofundme page and is gearing up to complete the five Great Walks of Southland in eight days.
He plans to start at Rakiura track on April 18 and then walk the Hump Ridge, Kepler, Milford and Routeburn tracks to raise money for humanitarian aid organisation Razom in Ukraine.
In five days he raised $12,000 but his goal was to raise at least €10,000 (NZ$15,700).
"Just like everybody else, I’ve been horrified by what has happened there. It is such an unnecessary invasion ...
"It is important that we are here in the bottom of the world and show them that we are thinking about them too and trying to support them."
Mr Lewis plans to end the hike on Anzac Day.
"I think Anzac Day is a very fitting day to be finishing — specially considering all the sacrifices Ukrainians have been doing to fight for their country and democracy."
