And as the teenagers gathered at 6am last Sunday for the longest day, one was heard to mutter it had been tougher than expected.
They got through, however, and made Mr Churchouse proud.
"We should never give up on our young people.
"Some have had difficult lives, more than we can imagine, but they didn't quit, so I didn't either," he said.
"These young people have taken huge, positive steps into adulthood, but they'll still stumble. Be there for them."
At the end of the longest day, after a physically exhausting early morning of sprints, burpees and a street run and having pulled a four-wheel drive vehicle up a steep hill, towing a 22-tonne, four-axle fire truck through the streets of Dannevirke and running more than 22km carrying water-logged power poles, wet bags of sand, tyres and ropes, up hills and through the bush, it was mission accomplished.
Ethan Rangi said he hated the heavy power poles, but overcome that hate.
"I'm going to miss my dad, Mouse [Mr Churchouse]," he said.
"He was our main soldier and such an inspiration to us all."
Mr Churchouse told the graduates they had cracked it: "You guys are awesome."
Top student was Rawiri Peachey, who always gave 100 per cent effort.
"He's just a machine. I don't know what I would have done without him," Mr Churchouse said.
Despite the pain, Jahleah Pakai survived the longest day.
"I'm sore, tired and my legs are burning," she said.
Other participants said the longest day had been the best day of their lives. But the eight weeks had, at times, been extremely difficult.
"Some of these kids we didn't even think would last the first week," Mr Churchouse said.
"We did have challenges, but week by week I saw them grow. But week six was a bit of a low point for me because we had a few struggling.
"However, I'm not a quitter and I didn't want to give up on them, so I really thrashed them.
"They were given 1000 crunches, 200 push-ups, 500 burpees and had to run up and down Riverdale Rd hill. Finally we had a team."
Cactus graduate Ashleigh Garvey said the students had all achieved much more than any of them expected.
Before the course, Ashleigh lacked the confidence to stand in front of others and deliver a speech, but at the graduation she was articulate and her head was held high, delighting her mother Hilary Hirst.
"It was a challenge worth taking and I now know I can do more than I thought I could," Ashleigh said.
* Full coverage of the longest day and graduation in Saturday's edition of the Dannevirke News.