Hours later 25-year-old promising MMA fighter Fau Vake was assaulted on the streets of central Auckland.
He died late last week.
Garnett, who has been training in the martial art of Muay Thai on and off for 10 years, said the idea someone may deliberately pick on him due to his fighting background remains a constant concern.
"Since I've been fighting, you expect people to pick on you, but it's not happened much," he said.
"Fighting in the gym has calmed me down and I don't look for fights, but you wouldn't want to fight people on the street anyway with the chance of them coward punching.
"It's just what people do these days – blindside people."
Four men have been arrested in relation to the alleged attack on Vake and are facing various assault charges.
Garnett said kickboxing keeps the fighting off the street and in the ring.
His recent title fight was scheduled for five rounds, but the former Zero Tolerance fighter needed only two.
"I'd fought the opponent before it was a hard fight and went the distance and I thought the same may happen again," he said. "But I trained harder and it paid off."
He dominated his opponent, scoring two early knockdowns as a result of powerful knees.
Garnett's coach Dallas Peneha, a trainer at Legacy Fitness in Onekawa and former kickboxing champion, said he is proud of the fighter's spirit and determination.
"We knew his opponent was a strong boxer, so our game plan was to kick on the outside then clinch and knee on the inside," he said.
"He always fights with 100 per cent heart."
After a five year hiatus from fighting, Garnett is next due to take to the ring in July and urged locals to take up the sport.