Cooper urged his 471,000 Twitter followers to "check in and ask #RUOK" even if friends did not seem to be struggling in their life.
"Guys shouldn't be afraid to reach out for help. It's a tough world out there," Cooper said.
SPORTING COMMUNITY REACTS
Rugby players, former rugby league players and cricketers all expressed their sadness at news of Vickerman's passing.
Former Waratahs and Australia teammate Phil Waugh had only positive things to say about his good friend.
"We all have huge admiration for the guy that he was," Waugh said, per Fairfax Media. "He was one of those players when you're standing next to him in the change room and he's running out next to you, you had so much confidence.
"He's a guy that necessarily wasn't the loudest in the team, but had the most respect from everyone playing with him. There's so many positive memories of him on and off the field."
β’ Lifeline: 0800 543 354 (available 24/7)
β’ Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
β’ Youthline: 0800 376 633
β’ Kidsline: 0800 543 754 (available 24/7)
β’ Whatsup: 0800 942 8787 (1pm to 11pm)
β’ Depression helpline: 0800 111 757 (available 24/7)
β’ Rainbow Youth: (09) 376 4155
β’ Samaritans 0800 726 666
β’ If it is an emergency and you feel like you or someone else is at risk, call 111.