TOM Berryman won't admit it, but the past 12 months has been arguably the most difficult period of his life.

In May last year the teenager complained of a sore arm which would later be diagnosed as the early stages of lymphoma.

From the moment he complained, Port Piranhas swimming coach Michael Mullens knew it was something real.

"He just doesn't complain about anything, this kid," he said.

"So when he did we knew there was something wrong.

"He was lucky he is a swimmer because you're always using your arms.

"Make no mistake, had it not been picked up, it could have killed him."

From May until January this year Berryman was out of the water and underwent chemotherapy but it didn't stop him from helping out with the Port Macquarie Swimming Club whenever he could.

He would still be a regular at training with a stopwatch in one hand.

Mullens said it was Berryman's positive outlook which helped him through.

"A couple of times he came back, watched the kids train and had a smile on his face," he said.

"I don't know how you can have a smile on your face after it but he was in a happy-go-lucky mood because that's just who he is. He doesn't complain.

"I've got no doubt his attitude has helped him get to where he is because he's a great leader."

Mullens said nothing surprised him about the 15-year-old.

"If he says he's going to do something he does it," he said.

"He's one of the best swimmers I've coached for many, many years and that's even taking into consideration James (Magnussen)."

The teenager was very matter-of-fact when asked what the most difficult part about the last 12 months had been.

There was no self-pity, he just got on with it.

"When I found out I had (lymphoma) I saw it as a little bit of a challenge and while it's something that was a little bit difficult it wasn't too difficult," he said.

"It's similar to what a lot of other people have to cope with so I took it as a challenge.

"Mum and dad kept asking me every five minutes if I was okay which was a bit tough at times because I'm used to being so independent, but they only did it because they cared."

Berryman was finally back in the water at the State Championships in Sydney last month and while slightly disappointed he didn't perform as well as he'd have liked, he said it was good to get back in the pool.

"It was mainly to see where I was at and give me something to build on because we have country championships in a few weeks," he said.

He doesn't see himself as an inspiration, but that's something which won't surprise people who know him.

"Everyone has struggles, it's just how you deal with it," he said.

He's already set his sights on the Commonwealth Games in 2018 and with the attitude he's already shown and hurdles he's overcome it would be a brave person to bet against him.