The Olympic gold medalist said that he fought suicidal ideation with the help of licensed professionals, crediting therapy with saving his life.
"I struggled with anxiety and depression and questioned whether or not I wanted to be alive anymore," he wrote on Twitter. "It was when I hit this low that I decided to reach out and ask for the help of a licensed therapist. This decision ultimately helped save my life. You don’t have to wait for things."
Phelps added that suffering from mental health issues is fairly common and announced that he's working with the online therapy company Talkspace.
"Did you know that one in four people around the world experience a mental health issue? I was one of them," he said. "That’s why I’ve teamed up with [Talkspace] this [Mental Health Awareness Month] –– to let you know that getting help is a sign of strength, not weakness."
The most-decorated Olympian of all-time has opened up about his depression before, noting that he pushed his problems aside during his competitive days and found that they came bubbling up after he was suspended from swimming competitively.
"After years, and years, and years of just shoving every negative, bad feeling down to the point where I mean, I just didn't even feel it anymore," he told Today. "It was a long, long, long road and I just never wanted to deal with it. And for me, that sent me down a spiral staircase real quick and like I said, I found myself in a spot where I didn't want to be alive anymore."