LUKE McDonald says he's fitter, stronger and counting down the days until he can prove he deserves his spot back in North Melbourne's best 22.

The emerging Kangaroos defender is in the midst of the best pre-season of his short career after battling a back injury last summer, and he's fiercely determined to put an up-and-down second season at Arden Street behind him.

Coming off a third-placing in the 2014 NAB AFL Rising Star award, McDonald admits he thought his form would just keep "rolling along" last year. 

Roos cop full force of brutal training session

But after missing out on North Melbourne's preliminary final loss to West Coast and realising a few "home truths", the 20-year-old has attacked his third pre-season like a man possessed.

"I haven't missed a session this year. It's been good to come back in much better shape and be able to do all the running with the top group and improve a fair bit," McDonald told AFL.com.au

"It's been a much better pre-season than any I've ever done before."

Leading into his third AFL season, McDonald feels like he's finally back in control of his body.

Since coming into the system, the courageous backman said he had struggled to balance the need to bulk up with maintaining his running ability.

"You've got to put on all this weight to match it with the boys, when at the same time you've got to match it with them in the running," McDonald said.

"The big thing (I had to improve) was just my strength in one-on-ones, and when I get tackled holding my ground. So I've done a lot of core stuff, which is good for my back as well. 

"I've put on about 10kg since I've been drafted (at about 80kg) and it's not like I feel I'm carrying it anymore, so I'm feeling good."

Having reflected on his 2015 campaign, McDonald said being dropped to the VFL after the Roos coughed up a 39-point half-time lead against Collingwood in round nine was the awakening he needed. 

"I was in the twos for a few weeks there and that was pretty frustrating. But I suppose it brought me back to a few home truths and then areas I need to work on to get back in the team – not just that but to be a consistent player," he said. 

"So I definitely got a real hunger. I just wasn't floating around anymore, I was really trying to improve to get my spot back.

"To finish the year and play 14 games … you go into each year wanting to play every game, so I was definitely disappointed with that.

"It was a very up-and-down year, but if anything it's spurred me on for this pre-season because I know I've got to improve to get my spot back and cement it."

McDonald has been working closely with development coach Gavin Brown to define his goals.

He's confident the Roos will be back up the ladder challenging for this year's flag after consecutive preliminary final appearances – and he wants to be a part of it. 

"We've definitely taken a lot of confidence over the last two years in our performances, not only in our structures and the direction (senior coach Brad Scott's) taken us, but also in our own ability that we do stack up against the best in big games," McDonald said.

"We've just got to get ourselves in a good position early in the year and I feel like we've got the list and the players on the park to do that at the moment.

"My first goal is to get through every session – but I want to have a better NAB Challenge because the last two I've missed games through niggles. 

"In a perfect world I'd like to play every NAB Challenge game and put my best foot forward, because I think that will carry a lot of momentum into the season hopefully."