The Warriors winger Manu Vautvei says he reached breaking point when he mixed prescription pills and energy drinks on a night out following last month's heavy loss to the Melbourne Storm.
Vatuvei was one of five players who was stood down from the side for one NRL game and from international play league after admitting to the incident.
Ben Matulino, Bodene Thompson, Sam Lisone and Albert Vete were all involved while Konrad Hurrell, was also disciplined although he denies taking the drugs.
Vatuvei was granted medical leave last week saying there were things he had been trying to deal with for some time.
"Last week (going on medical leave) was (for) something that has been going on for a long time.. when you bottle up a lot of things in your head for a long time - that was my breaking point and something that I am working on now.
"My body is ready to play but my mind's not there," he said.
Vatuvei said the players were "embarrassed" by what they had done, and as a long standing club member having played 215 NRL games it was not something he was proud of.
The Warriors play the Penrith Panthers in Christchurch this weekend.
It will be their first game in a fortnight after a weekend break during the international window when New Zealand played Australia.