The Kumuls looked to be tight-knit and were in good spirits during their training sessions throughout the week, frequently sharing jokes and laughter.
After Tuesday's session in the afternoon heat, players took turns at standing up in front of their team mates and told a brief story about an amusing incident on camp so far.
"(It's about) not thinking too much on the game itself. Come Sunday, you just want to go out there and enjoy the football," Marum said.
The Kumuls are unbeaten in their three pool games so far and the coach expects the intensity to lift against an experienced English side.
"We did well to win our World Cup games at home, but we had home crowd support. I expect real football down here. We expect a tough challenge against the English side. They have experience all over the park, and all their players are from Super League and the NRL," he said.
"We're just going to do our best for our country."
Marum says he's focused his preparations on ironing out some defensive issues that crept into PNG's game at times.
"We understand the last three matches, we only gave away three tries and they came from kicks. They (England) are big, mobile, play a bit of football, but if we make sure we defend well against them and make sure they don't get to offloads then we will be in for better chance."
The coach also spoke about how the PNG Hunters' success has flowed throughout the team. Many of the Kumuls played during the year in their Queensland Cup premiership.
"The Hunters program they've put in place has really helped this side," he said.
"Those players are playing week in, week out in the competition – it's really good experience for them. Together with the NRL boys and the Super League players coming in, it's certainly helped the side.
"We seem to have a good mix, they enjoy each other's company."