There is no way to describe the jungle path up Mount Murud, Sarawak's highest mountain, except for tough and tougher.
It is relentlessly steep, with numerous fallen trees blocking the way, forcing walkers to climb over or crawl under them.
It is made even tougher by the slushy mud and so many tree roots littering the path that walking becomes more of an exercise of skipping than a steady one foot in front of the other.
Despite the hardship, hundreds of people, fit and unfit, make the two-day climb every alternate year in a unique Christian pilgrimage in the Malaysian state on Borneo island.
The mountain is regarded as a holy place for Christians of the Protestant church of the Borneo Evangelical Mission (or Sidang Injil Borneo (SIB), as it is known in Malay).
SIB is a small but fast-growing Christian denomination in Malaysia, with a significant part of its membership coming from beyond Borneo. Having its roots in the deep interior of Borneo, it has strong appeal as a home-grown denomination with traditions and stories that are derived locally.
Mount Murud is central to the faith.
The biennial pilgrimage draws the faithful from afar, such as Hong Kong and South Korea and even Africa, for the trek and three-day prayer meeting.
Ms Christina Foo, who made her first trek in 2011, said she first heard about it during a church conference in Kuala Lumpur, and decided to go with two other friends despite not knowing anything at all about Mount Murud.
"My heart wanted to go but I was worried," said Ms Foo, 42, a teacher from Kuala Lumpur.
The jungles were unfamiliar to her, and her fears almost came true when in the first 15 minutes many of the first-timers wanted to turn back because it was so steep and tiring.
"At some points, I cried," she said, adding that the silence of the jungle was also unnerving.
But they persevered, with the help of the locals who carried their belongings for them.
Everything, from clothing to food for four to five days, has to be carried up. That includes warm clothing as the temperature on the mountain can fall to 13 deg C at night.
The journey begins at the village of Ba Kelalan, a remote settlement in the north-east Sarawak mountains that lies close to the border with Indonesia.
The full walk takes two days of steep jungle trekking, occasionally enlivened by leeches. The overnight stop is at a rudimentary shelter with no water or electricity, or other niceties.
Fortunately, there is now a dirt road that will halve the walking time but the road is not always usable if heavy rains turn it into a slippery mess.
The concept of a prayer mountain is common in Sarawak villages where nearby hills and mountains are designated as a place of prayer. In symbolising the search for God, the climb is usually a difficult one but there is a reward of vast views upon arrival.
"I feel the walk itself is very significant. It makes your wanting to hear God even greater. And in walking there, you become ready to hear God speak to you, and you leave all your worries behind," said Ms Foo.
Mount Murud, at 2,424m, is the highest of the prayer mountains, and definitely the toughest one. It is Malaysia's fourth-highest peak.
It became a prayer mountain after a local man from Ba Kelalan, by the name of Agung Bangau, had a vision which directed the people to build a church there in the 1980s.
His vision, according to the local people, was very specific, right down to the exact location. It was to be at a spot where a giant tree grew, which later provided the timber to build a church.
At that time, there were also many unexplained events in Ba Kelalan such as sightings of fireballs and water turning to oil - all of which were seen as signs sent to the people for their faith.
Mr Tagal Paren, 81, one of the oldest residents of Ba Kelalan, said these miraculous signs were encouragement to the people to obey the directive to build a church on Mount Murud.
Before that, they avoided the mountain, believing it filled with spirits. Even their parent church regarded their wish to build a church there as misguided.
"But still, we carried out what God has instructed," he said.
At that time, it took four days to walk there without much semblance of a path through the forest.
They did not know how to get to the summit but followed Mr Agung, who passed away about a decade later.
The people, thus, began building a church on a mountain plateau, later named as Church Camp.
And today, there is virtually a whole village there. There is a huge church that can seat 1,000 people, about 100 houses and public amenities such as toilets and bathhouses, all linked by a wooden walkway.
Building it was one of the toughest tasks ever for the people of Ba Kelalan who are, by nature, very hardy and strong.
Other than wood, all the material had to be carried up on the backs of the people from the village. They brought up chainsaws to cut timber from the forests.
The first prayer meeting was held there in July 1985, with over 600 people from Ba Kelalan and the neighbouring settlement of Bario.
Soon, more and more people began to join them on the mountain. Since then, a prayer meeting is held alternately on Mount Murud and in the village every July.
The story of the village's faith, though, begins much further back.
More than a hundred years ago, the people of Ba Kelalan, who are of the Lun Bawang ethnicity, were famed for their drunkenness and war-mongering. They were a community that was dying out from wars and disease.
But a remarkable change came about in the 1920s when Australian missionaries braved their way to this remote area, bringing health and education services with them.
The SIB church was set up in these highlands, before spreading beyond Sarawak and Sabah.
The Lun Bawang community is today a high-achieving minority ethnic group in Sarawak.
They still take their faith very seriously to the point that drinking and smoking are seriously frowned upon in the village.
Mr Pudun Tadem, the former principal of the Ba Kelalan primary school, said the pilgrimage is a key part of their Christian faith because the people wanted to honour what God had told to them through Mr Agung in the 1980s.
He said that, over the years, people from practically every corner of the world had come to Mount Murud.
"We are not well-off financially, so we cannot go out to the people. But through this, people can come to us. The world comes to us," he said.