For the budding rugby star, it was a form of expression which moved him to dig deeper, run faster and push further as he worked to become the best sportsman he could be.
On April 20 this year, the music stopped.
The 16-year-old was on an early morning run when he was tragically struck by a train and killed in Ranui, West Auckland. He had been wearing headphones at the time.
Almost two months on, the Massey High student's parents have joined an international campaign calling on people to drop at least one of their headphones when out and about, in a bid to save lives.
The "One Ear Out - Tune in to life" campaign was started last year by the family of Amanda Kirchner, 20, in Westminster, Colorado, in the US. She had been walking to work, with her headphones on, and was struck and killed by a train in August last year.
Matthes and her husband Presley were approached by Kirchner's family to share their story and to join the campaign to help spread the word in New Zealand.
The couple and Keenan's younger sisters, Kalani, 11, and Cecelia, 5, have been spreading the message within their family and wider communities.
"We live in a world of distractions and it's easier to be distracted now more than ever.
"If you can't hear your surroundings, or if you're so focused on your device ... you're deaf and blind to what's happening around you. So we need to let the kids know, just be careful when you've got headphones in.
"If you're running and you're around tracks, around busy roads, just be focused and be aware of what you're actually doing instead of being so hooked into technology.''
At the family home in Ranui, family pictures and photos of Keenan in his high school and North Harbour rugby rep shirts surround the living room.
Just beyond the backyard, the train station and tracks can be seen.
Her voice breaking, Karamea Matthes recalls she had just finished her breakfast that fateful morning and had been on Facebook when she saw people talking about an accident at the tracks.
She called Keenan's phone, but it went straight to voicemail. She dashed down the road in her car and stopped a policeman to ask what had happened.