As one of the first Outward Bound instructors in the late 1960s, he remembers having to build everything from the ground up.
"We had to construct our obstacles from scratch. I remember climbing the casuarina trees and tying ropes onto them," said Mr Mathias Chay, 70, who started out at the Outward Bound School, which was renamed Outward Bound Singapore (OBS) in 1991.
Mr Chay, who went on to spend nearly a decade as an instructor, was one of more than 200 guests at a dinner held last night to celebrate 50 years of OBS.
Minister for Culture, Community and Youth Grace Fu launched the OBS50 campaign - a six-month drive to recognise the outdoor education programme's impact on Singaporeans' lives.
Those who have been through OBS are encouraged to share their experiences on Facebook or Instagram using the hashtag #myOBSstory. Some of these will be compiled into a book on how it has changed. More than 500,000 young people have been through OBS since its launch in 1967.
"A stint in OBS is transformational in so many ways," said Ms Fu, who is also chairman of the National Youth Council.
"Having gone through such physically and mentally challenging obstacles, you learn to push your limits and overcome your fears; and in doing so, you discover your potential."
OBS has two campuses on Pulau Ubin, with a new campus on Coney Island coming in three years' time.
From 2020, all Secondary 3 students will have to go for a five-day camp, which brings together young people from different schools.
Other OBS50 events planned over the next six months include an outdoor education conference and an open house for OBS alumni. The celebrations will culminate in an anniversary dinner in October.
Ms Poh Hui Yi, 24, who went through a three-week OBS stint last year, said it taught her leadership skills as well as how to work as a team, even with people much younger or older than she.
One of their first tasks was to spend four days trekking around Pulau Ubin with only a map and a compass, with each member taking turns to lead the group.
She said: "The challenges in the first few days were both physical and mental because we didn't know each other, but after that everything went well. I felt that the instructors at OBS really made it a point to help us grow individually."