A month out from the start of the NRL season, rising Warriors star Shaun Johnson has admitted he is still being hampered by a bulged disc in his back.

But the 21-year-old insists it will not affect his ability to play this year. After a breakout NRL season last year, Johnson was offered a place in the Kiwis' Four Nations squad but declined in order to let his problematic back heal.

He believes it has already improved significantly and is adamant missing a potential first Test cap was a price he had to pay to be right for this year's NRL campaign.

"I played with a bulged disc in my lower back throughout the whole of last season," he told the Herald. "I wanted to give myself the best possible chance to get that right and I knew that this year, after last year, was going to be a big one for me.

"I wanted to be at my best and it was a really tough decision to turn down the Kiwis because growing up it was always a dream of mine. But I'm glad I did it now. I'm feeling a lot better and while my back's still not 100 per cent right, it's heaps better."

After making his first-grade debut against the Roosters in round 13 last year, Johnson went on to star for the Warriors, playing 16 games including the grand final.

In November, the club moved quickly to re-sign him until the end of the 2014 season and Johnson knows the pressure will be on him to step up again this year.

The NRL is full of players who starred in their first year only to fade into obscurity, but he has no intention of adding his name to the list.

"It's pretty hard not to be aware of the 'second year blues' when everyone talks about it," he said.

"But I'm just trying not to think about it. I've been trying to do what I did last year and what I've always done. It's about training hard and not stressing about things too much. It's just footy, right?

"It's something I've always done and something I've loved.''

Aaron Lawton