RYAN Harwood admits he made a big mistake in the 2010 off-season - a mistake he plans on rectifying.

This time last year the 20-year-old Lion had just completed his first full season at an AFL club and thought it was time to put his feet up.

When he returned home in Tasmania, footy was the last thing on his mind.

"I got too involved back into my social life more than my footy, got around the mates and got into bad habits again that I had before I got drafted," Harwood said.

It was a mistake that would cost the talented midfielder.

Harwood returned for pre-season training unfit and out of shape and struggled to recover all season.

He was never a great runner as a junior and his lack of fitness limited him to just seven senior games in 2011 after six promising appearances in his debut season.

Harwood was taken by the Lions with the 47th pick in the 2009 NAB AFL Draft following All-Australian selection at the under-18 championships.

His clearance work is exceptional, as is his ferocity for the contested ball, but Harwood admits his fitness is holding him back.

"I was pretty bad last year. Now I know what I've got to do in the next few weeks when I go home," he said.

"I didn't find out running was such a big part of the game until I played AFL. When you're in juniors and under-18s you can get away with it, but not at the top level, you have to be top notch.

"With the new sub rule, blokes need to be on the ground for longer periods and that was a big issue for me. I could only sustain a certain amount of time before I needed a rest and I need to get on top of it. I'll work hard in the off-season.

"I'm definitely keen to get rid of my reputation of not being able to run."

Harwood now has a program to follow and said he would try and team up with fellow Tasmanian and Lions teammate Tom Collier, as well as a junior fitness coach in the coming weeks.

The Lions showed their faith in Harwood earlier this year by extending his contract for a further two seasons.

Harwood said he was eager to break into a midfield rotation that was becoming more settled with Simon Black, Tom Rockliff, Jack Redden and Daniel Rich leading the way.

"I want to stay here for as long as I possibly can and I want to show more of what I've got," he said.

"It's going to be a good challenge but hopefully I can squeeze in there somewhere."

Michael Whiting covers Brisbane Lions news for afl.com.au. Follow him on Twitter: @mike_whiting