Knowing her brother had spent several nights in the bush where temperatures had dropped below zero at night was taking its toll on the family, said Margaret Kumar.
"We're pretty much trying to hold it (together) at the moment but it's pretty hard because he went missing on Saturday and it's Tuesday, and we're just worried about what he's going through,'' she said today.
"My brothers are slowly breaking down and for myself, I'm starting to crack today. I'm really freaking out,'' she said.
Mr Fong, a bio-engineer at Middlemore Hospital, was wearing only a T-shirt, lightweight jacket and three-quarter length shorts and carrying a backpack with a bottle of water, Powerade and a box of Nutri-Grain.
On Saturday he was in a good mood and looking forward to the tramp, Ms Kumar said.
He usually went with friends but as no one was free to go with him that day, he decided to go alone.
Her brother, who did rock-climbing, martial arts, and tramped weekly, would be resourceful in the bush, she said.
"He'll probably panic for a little while then I know he'll figure out, 'I've got to stay alive'. He's quite a strong person.
"I just hope the Lord brings him back to us safe and sound. We're praying''.
