The recently retired Tigers great says he was in a "dark" space three years after being appointed captain in 2013 at the age of 22.
"I did a s*** job at it to start with, to be completely honest with you," Cotchin told Triple M's The Rush Hour with JB and Billy on Wednesday.
"The end of 2016 for me was a moment where I genuinely questioned whether I should be the captain of the footy club, whether I wanted to play footy anymore.
"I got to a pretty dark place and probably hadn't shared it with a lot of people other than my wife Brooke and maybe two or three others within my circle.
"As captain, what I thought was that I didn't want to burden anyone with the challenges that I was going through.
"You know, 'I was the worst captain, Dimma (Damien Hardwick) was a crap coach, he should be sacked'; we had a board coup going on at the end of 2016."
The next season, Cotchin led the Tigers to the first of three flags in a dominant four-year span.
"To think about the transformation that happened from '16 to '17, the enjoyment we had across the year," he said.
"And that wasn't just on the basis of winning games of footy.
"It was just the every day and celebrating those little moments, which are the memories we talk about now when we get together as a premiership team."
Cotchin counselled his famed Tigers teammate Dustin Martin when the triple Norm Smith medallist was a rumoured target for Gold Coast under new coach Hardwick.
"There's always that carrot that's being dangled, particularly when someone you love and trust goes up there to coach the footy club," Cotchin said.
"You know, he has every right to contemplate it. We had conversations around it.
"But he's pretty passionate and knows that the club has still got some great years ahead of them, and he's got some great footy ahead of him as well.
"He really does like the idea of making that 300 milestone (at Richmond) ... it would be pretty special for him to join that club."
Martin, on 289 games, is set to join Kevin Bartlett, Jack Riewoldt, Cotchin, Shane Edwards, Francis Bourke and Jack Dyer as Richmond 300-gamers next season.
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