When he was five years old, he was hit in his left eye with a BB.
Doctors performed surgeries and managed to save his eyesight, but after just a few months he was playing again with a bow and arrow.
As luck would have it, an arrow struck him in the eye.
Trenholm hid the wound from his parents and the infection spread quickly.
At the age of six his left eye was "yanked out."
He believes he was the first in North America to undergo cornea transplant surgery when he was 16. But it wasn't successful, and his right eye was removed.
"I was hell bent to be a blind person," Trenholm said with a laugh. "Just the type of accidents I had you'd have a hard time making them happen again if you set out to do it."
His blindness hasn't stopped Trenholm for becoming a successful businessman. He is the co-owner of Doctor Piano in Halifax, which sells, tunes and moves pianos — from a popular upright model to a $90,000 Steinway grand piano.
He's proud to say the business was established in 1977.
Trenholm tunes pianos, although he spends most of his time managing the store's day-to-day operations.
He can also move pianos like nobody's business, except that it is his business.
"They're heavy and they're awkward," he said. "You have to make sure you keep it balanced all the time."
Despite not being able to see, the mover has never had to file an insurance claim for causing major damage.
"Most everyone who calls us, it's through word of mouth and word of confidence. All of the institutions, from the Maritime Conservatory [of Performing Arts] and Dalhousie and Acadia and St. FX [universities]. All the schools and the teachers," he said.
"It's got to the point now where I'm trusted enough that people will say 'Go see Gary and he'll take care of you.' That's great."
He chalks up his skill to experience.
"I don't stop and think how these things are done very much. You sort of operate on instinct a lot of the time," he said. "When you go to put your shoes on, you have a pretty good idea where your feet are all the time."
Watch the video and see how he does it.