Cameron Smith and Johnathan Thurston at the NRL launch.

Cameron Smith insists he's undecided whether he will play on beyond the end of 2018 but is conscious of not going "a season too long".

The Melbourne, Queensland and Australian captain is off contract at the end of this season but is likely to become the first player to break the 400-game barrier should he play on in 2019.

The Storm skipper achieved everything in the game last season, winning a Telstra Premiership, Holden State of Origin series and World Cup on the way to being crowned the Golden Boot winner.

However, he doesn't want to reach a point where he is no longer able to maintain the incredible standard he has maintained throughout a decorated career.

"I have always thought I would never stay too long," Smith said at the NRL season launch  in Sydney on Thursday.

"I don’t not want to go a season too long, not play well and everyone say you should have got out. I would rather finish while I am still playing strong.

"Family is a big part of my life - a bigger part of my life than what rugby league is now. That will play a huge part in my decision about whether I play again next year. At the moment in my mind I am not clear about whether I will play next year."

One of Smith's closest mates, Cowboys captain Johnathan Thurston, believes Smith will have no problems playing for another two seasons.

However he realises there's a family component to the decision.

"I think he could easily go around another year and I hope he does, actually," Thurston said.

"I’m being selfish, but I’d like to see him go on and make 400. It’s within reach but I’m sure his wife has got other ideas."

The Storm went through an entire season of contract speculation in 2017 surrounding Cooper Cronk and Billy Slater, however it didn't prevent them from winning a premiership.

Smith knows there will be similar interest in his future intentions throughout their title defence but won't be rushing into a decision.

"I tend not to have my career played out in the media," he said.

"It was a different situation with Coops as well because he announced early that he was leaving the Storm. I don’t have any plans to do that.

''If I wasn’t to play with the Storm next year that would probably mean my retirement. So there’s not going the as much speculation around my future as with Cooper. But there are always going to be questions about what I am going to do next year.

Melbourne Storm captain Cameron Smith.
Melbourne Storm captain Cameron Smith. ©Grant Trouville/NRL Photos

"For me, my sole focus has been about getting myself physically prepared for this year. I haven’t put any thought at all into 2019 to be honest and make sure that I start well and the team starts the season well. Once that happens, I can have some discussions with the club and see where they are at next year."

While Slater is all but certain to call it a day at the end of this year, Smith says the decision of his teammate won't have any impact on what he decides to do.

"As far as Billy’s position and whether that impacts on what I do, it doesn’t have any impact at all because I don’t know what Billy is thinking, I don’t know when he will decide what he is doing," he said.

"He might wait until the last game of this year to decide what he is doing, like he did last year. No one knew last year until after the grand final including the coaches and his teammates.

"If the discussion arises around my future sometime soon, and I am happy to go ahead with those discussions, I will have those discussions without knowing what Billy is doing."