FOR A man that's missed a season-and-a-half in the prime of his career, Allen Christensen seems remarkably content.

The clever Brisbane Lions half forward has suffered two collarbone fractures in the past 18 months and also endured a crack to the plate used to strengthen the area.

He hasn't played since former Carlton star Andrew Walker cleaned him up in round 11, 2016.

Now, with the area back to full strength, Christensen is itching to play again next season.

"I'm a bit nervous," he told AFL.com.au at the Lions' pre-season training camp in Launceston.

"The game has changed since midway through last year so much.

"We play a different game to when 'Leppa' (ex-coach Justin Leppitsch) was here.

"Like some of the players, I'm still getting used to some of the structures because I haven't been able to implement them in games, yet.

"It's exciting. I'm obviously going to be pretty nervous when we run out, even if it's a pre-season game.

"Hopefully it's like riding a bike."

Christensen hasn't played under Chris Fagan yet, but says he's been excited watching the development of the young players under his guidance.

The former Geelong premiership player is in the Lions' leadership group and one of the most popular – and chatty – players at the club.

He's one of the loudest voices of encouragement at training and also isn't shy to "get on" teammates if he feels it's justified.

Fagan has described Christensen as a virtual new recruit in 2018, with his strong decision-making expected to add to the half forward and midfield mix.

It's been a long comeback.

Christensen won a premiership with Geelong in his first season in 2011 and has played 98 games in his seven seasons in the AFL.

He said he was "sad" at times during his rehabilitation, but now back into full contact, his focus is single-minded.

"I've taken the approach that if it happens again, it happens again," Christensen said.

"I'm going to put myself into situations where it could break again. It could break for anyone.

"I think it's a pretty important mindset to have.

"I'm probably more likely to hurt it if I go in half-arsed.

"That's my game, getting the ball out of contested situations and making decisions to help my teammates.

"I can't wait to get out there."