Johnny Manziel said on "Good Morning America" on Monday that depression and bipolar disorder played a major role in the substance-abuse issues leading to his NFL exile.

"I was self medicating with alcohol because that's what I thought was making me happy to help me get out of that depression to a point where I felt like I had some sense of happiness," Manziel, the former Heisman winner and Browns quarterback said Monday, via "But at the end of the day, when you wake up the next day after a night like that or after going on a trip like that, and you wake up the next day and that's all gone.

"And that liquid courage or that liquid sense of euphoria that's over you that's all gone and you're left staring at the ceiling by yourself and you're back in that depression and back in that hole, that dark hole of sitting in a room by yourself and being super depressed again thinking about all the mistakes you made in your life. Where did that get me? Where did that get me except out of the NFL? Where did it get me? Disgraced."

Manziel said he stopped drinking last year, that his mental health is the main priority right now and that the help of medication for depression and bipolar disorder has made a big difference in his life. Manziel's revelation that mental health issues contributed to his substance abuse isn't unique; studies indicate up to 60 percent of addicts also suffer from mental health issues.

"I went a solid five months until I really fell back into a little bit of a depression where I didn't drink, I didn't do anything, but still I was going to therapy and the difference that I know this year is I started taking a look at my mental health a little bit and making it a priority in my life to where I'm taking medication for bipolar and I'm working to try and make sure that I don't fall back into any type of depression because that leads me... I know how slippery of a slope that is."

Manziel was last suspended by the NFL for four games in June 2016 following a failed drug test less than one year after he spent nearly three months in rehab.

Should he ever receive another opportunity in the league, he'd still be subject to further discipline for a 2016 arrest on a domestic violence charge that was later dropped. Manziel was accused by ex girlfriend Colleen Crowley in Jan. 2016 of grabbing her hair and hitting her ear, leading to hearing loss and a misdemeanor charge of domestic violence. He was quickly released following the incident by the Browns, ending a turbulent two-year run with the club, and dropped by agents and sponsors.

Manziel last year got engaged to girlfiend Bre Tiesi. Along with Manziel's mom and dad, Tiesi, Manziel said, has witnessed the change he's undergone from NFL star dealing with entitlement issues and partying recklessly and relentlessly to one committed to his recovery. Manziel acknowledged there's a long way to go toward reaching his goal of again playing in the NFL.

"The question is, is that sustainable and will that be the case going forward? I would like to say yes. I have a lot of confidence that would be the case. But at the end of the day, it's to be seen. I'm still moving forward. I'm doing the little meticulous things I have to do on a daily basis to try to keep this (points to head) right and everything else means the most to me. The main thing for me is not physical health, it's mental."

Whether Manziel's only current football opportunity — with the Canadian Football League's Hamilton Ti-Cats — can eventually be parlayed into a second NFL shot, he admits, is unclear.

"I'm coming back from a huge downfall. I don't know what kind of comeback it will be. But I know I want to get back on the football field and do what brought me so much joy."