EXCITING young Fremantle midfielder Lachie Weller wants to play his entire career with the Dockers.

Weller, 19, made his AFL debut last season playing three games in his first year at Fremantle after he was recruited with pick No.13 in the 2014 NAB AFL draft.

He signed a two-year contract extension in November to tie him to the club until the end of 2018 and on Monday declared his desire to be a one-club player.

"I'm really happy, it's a great club and I want to play my whole career here," Weller said.

He said there was never any thought of moving elsewhere despite interest from other clubs, including St Kilda where his brother Maverick plays.

Weller originally hails from Tasmania but spent three years in Queensland prior to being drafted by the Dockers. 

He has settled into life in Perth living with teammates Connor Blakely and Ed Langdon. His girlfriend has also moved over to live with him this season.

Like Blakely, Weller said he had put some weight on during the pre-season in a bid to become stronger over the ball.

"It's a slow process," Weller said.

"You can't put the weight on really quickly. You can get injury-prone and things like that. I managed to put on a couple (of kilos) in the off-season and I'm happy with the weight at the moment.

"I just think all AFL bodies out there now, they're hard and they're strong. It's a big focus for young players coming through the door."

Weller said he had spent most of this pre-season working with new assistant coach Anthony Rock on his bodywork in contested and stoppage situations.

"He was a hard inside player," Weller said.

"That's the sort of aspect I'm working on a little bit. He's been working with me on touch and body work."

Weller also said he was learning from Michael Walters and Hayden Ballantyne about how hard he needs to work as a half-forward/midfielder.

"I love the way Sonny Walters and Hayden Ballantyne go about it," Weller said.

"Playing up forward with them, they work so hard and it's what I look up to."

Weller said he was hopeful of playing a part in the NAB Challenge.

The Dockers' opening game is against Richmond at Rushton Park on February 19.