Recruited as a promising 192-centimetre utility from South Australia, Mackie weighed a mere 73 kilograms when he arrived.
Endless hours in the gym and a solid VFL season means Mackie is one of a number of young Cats likely to make a contribution this year to a much-improved side.
"I'm aiming to get to about 85kg by the start of the season, in the last 12-13 months I've put on about nine kgs and this pre-season we've increased all the weights so I can feel the difference," Mackie said.
"You look at people like Ben Graham, Matthew Scarlett and Steven King and think they had to start off somewhere too, and even now Matty McCarthy and these blokes, so you have to keep doing the hard work and it'll come. You have to be patient."
Despite being a long-term project, last season Mackie still carried the expectations associated with being a club's No.1 choice in the national draft.
Although he's not expected to make a sizeable impact this year, Mackie doesn't hide the fact that he wants to play senior football and the opening Wizard Cup game against Port Adelaide is in his sights.
"(Seniors) is the number one goal, not playing last year makes you think about it a bit so it's the main goal and that's what you're here for," he said.
"I haven't (set any game targets) as yet, I'll sit down soon with Ken (Hinkley) and Cressa (Daryn Cresswell), but (the Wizard Cup) is a goal.
"I've put more pressure on myself this year, last year I knew that playing seniors would have been a bonus because I was skinny …you do think about it."
Mackie's light frame means if he is to play seniors he will probably be used as a midfielder or half-forward flanker, his pace and endurance meaning he's not restricted to a key-position role.
His development in the VFL side certainly pleased Cats officials, who will this year be expecting him to play a pivotal role when he lines up for them.
"I was happy without setting the world on fire, I was a bit inconsistent during games, I would have good patches and then fade away for a bit, so I've just got to get consistent and play four quarters," Mackie said.
"I remember the first game against Port Melbourne, you run around trying to see what people do, and still try and get the footy and by round 22 you encourage and talk instructively and feel comfortable."
