Michael Phelps is well equipped to understand how Simone Biles felt after the living legend withdrew from the women's gymnastics team event in Tokyo on Tuesday, saying she needed to "focus on my mental health and not jeopardize my well-being."

And Phelps, an outspoken advocate for mental health care in athletics, said it broke his heart to learn of her mental anguish.

"We're human beings," Phelps said. "Nobody is perfect. It's okay to not be okay, to go through ups and downs. The biggest thing is we all need to ask for help. I can say personally it was very challenging. It was hard for me to ask for help. I felt like I was carrying, as Simone said, the weight of the world on my shoulders. It's a tough situation."

Biles competed in Team USA's first rotation on vault, bailing out of her Amanar and scoring a 13.766 for a 1.5 twist. She was then seen walking off the floor with her bag and a trainer. 

She'd later explain her withdrawal was due to mental health concerns, which came before the Americans rallied to win silver.

Phelps has acknowledged his struggles with depression and even thoughts of suicide and how he dealt with it, later becoming a mental health advocate.

He gave his unique perspective to Mike Tirico Tuesday evening on NBC.

"The Olympics is overwhelming," Phelps said. "There are a lot of emotions that go into it. The easiest way for me to say it is, talking about weight of gold, is we need someone we can trust. Someone who can help us be ourselves and listen. Someone who's not going to try and fix us. We carry a lot of weight on our shoulders and it's challenging especially when we have the lights on us and all of these expectations.

"It broke my heart but also, if you look at it, mental health over the last 18 months is something a lot of people are talking about."

Phelps later said that he thinks Biles joining the crowd of major stars in speaking on mental health could be another tipping point for a challenging and important issue.

"I hope this is an eye-opening experience, an opportunity for us to jump on board and blow this mental health thing even more wide open," Phelps said. "It is so much bigger than we could ever imagine."