Boyd Cordner has opened up on his heartbreaking decision to retire early from footy as the NRL star lifted the lid on life after multiple concussions.

Cordner, the former captain of the Roosters, Blues and Australia, retired aged 28 after an injury and concussion-plagued career. In 11 seasons, he made only 183 NRL appearances.

And speaking on SAS Australia, Cordner revealed the mental turmoil of retiring early, and the side effects that concussion continues to have on him.  

'In 2020 I retired from concussions,' he said. 'I still suffer symptoms now, especially with the constant headaches and the lightheadedness sometimes and the sensitivity to the light and noise.

'It's disappointing. I've had countless injuries since I was a kid and late in my career went through a tough trot with concussion. Dealing with symptoms of concussion, I would have days where I would break down crying. It was all a bit too much for me.  

'I was the captain of my club, state and country at that time and that was the toughest time mentally. At the end of the day it was my decision. I didn't know what the next head knock would bring. 

'I had to put everything into perspective and work out my long term priorities. Memories are everything and they make up who you are as a person. Those memories are priceless.'

Cordner also reflected on his relationship with his mother, who died when he was just four years old. 

'It's not until you're older and look back on your childhood, and you think as good as it was, how different it would be if she was there or if she was still there guiding me or there to be a mum.

'You'd change everything to go back and have mum back, but I've been blessed with the best-loving family.'

Cordner's future on the show is uncertain after he suffered a serious injury during one of the tasks. The contestants were asked to climb a rope into a helicopter above the sea but, as he jumped towards the rope, Cordner tore his pectoral muscle.

'It's quite a scary thought when thinking about what might stop me from completing  the course is my old body breaking down,' he said.

'If I had to quit or if I had to take that armband if I'd feel like I've failed for sure. 

'I am my own worst critic and I know when I haven't done something right. I beat myself up about it.'