Michael Phelps—the most decorated Olympic athlete of all time who won 22 medals, 18 of them gold, in swimming in four Olympiads—was so despondent in September 2014 that he thought of ending his own life, ESPN Magazine revealed in its July 18 issue.

"I was a train wreck," Phelps told ESPN. "I was like a time bomb, waiting to go off. I had no self-esteem, no self worth. There were times where I didn't want to be here. It was not good. I felt lost."

It was during that time when a photo emerged showing him smoking drugs. He had also been arrested twice in 10 years for drunk driving—the last one on Sept. 30, 2014 when his life "hit rock bottom."

The days that followed saw Phelps staying mostly in his bedroom in his Baltimore home, thinking about suicide.

At that time, Phelps said he was thinking, "This is the end of my life... How many times will I mess up? Maybe the world would be better without me."

Phelps said he isolated himself, didn't eat, and hardly slept for at least a week as he continued nursing the idea of killing himself.

But then his long-time Christian friend, NFL star Ray Lewis, came to his rescue. Lewis called up his buddy and told him, "This is when we fight. This is when real character shows up. Don't shut down. If you shut down we all lose."

Lewis convinced Phelps to seek help at the Meadows, a behavioural rehab facility outside Phoenix.

Phelps heeded his friend's advice and entered the rehab facility carrying a book Lewis gave him, "The Purpose Driven Life," by Rick Warren.

After reading the book for a couple days at the Meadows, Phelps called Lewis. "Man this book is crazy!" he exclaimed. "The thing that's going on...oh my gosh...my brain, I can't thank you freaking enough, man. You saved my life."

Phelps told ESPN that the book "turned me into believing there is a power greater than myself and there is a purpose for me on this planet."

Warren's book also convinced Phelps to reconcile with his estranged father, Fred, who divorced his wife when Phelps was just 9 years old.

When the two men saw each other for the first time after so many years of separation, they embraced in a big hug.

After he left Meadows in November 2014, Phelps resumed training for the Rio Olympics.

Three months later he asked his long-time girlfriend, Nicole Johnson, to be his wife. Last May 5, Johnson gave birth to Boomer Robert, their firstborn.

The American legend showed he still has what it takes to be a champion in multiple events, swimming the fastest 200m individual medley, 100m butterfly and 200m butterfly at the 2015 US National Championships.

As he was celebrating his 31st birthday on June 30, Phelps qualified in three individual distances, plus possibly three relays, for the US Olympic swimming team in Rio.

Phelps said Rio 2016 will be his fifth and last Olympics.