SYDNEY ruckman Sam Naismith has put a tough 2018 behind him by re-signing with the Swans until the end of 2021.

Naismith did not play a premiership game this season after rupturing his right anterior cruciate ligament late in the pre-season.

However, the former rookie had shown enough over the previous two seasons and in his rehabilitation for the Swans to reward him with a three-year contract extension this week.

"It shows that the club really wants me here and it's a show of faith that they see me here long-term," Naismith said on Wednesday.

"That's a really good incentive for me to push myself and really repay the faith.

"My pre-season's pretty much started. I'm ready to get stuck in and hopefully when we come back I'm a few steps ahead of everyone. Then I can join in with the skills and take it from there."

While on the sidelines, Naismith has done some coaching with the Swans' NEAFL team, working alongside development coaches Tadhg Kennelly and Jeremy Laidler.

"Just helping out on game day with Tadhg Kennelly with the younger generation coming through has been great," Naismith said.

"It's been really beneficial to sit on the sidelines, sit in the box, help Tadhg with positioning, helping with rotations, seeing it from a different perspective.

"When you're out on the field it's a lot different to sitting up in the box."

Since joining the Swans in the 2013 Rookie Draft, Naismith has played 28 games, all bar one of them in 2016 and 2017.

Naismith became a key player for Sydney after Mike Pyke's retirement at the end of 2015 and was particularly influential in the Swans' run to the 2016 Grand Final.

"The people around the club have been great for me this year," he said.

"It's been a tough year for me and the support that I've had and the friends that I've made here have been great."