This year, America’s most decorated athlete returns to the summer Olympics after years away from sports. But, despite all of his success (he’s already won 18 gold medals), Michael Phelps has had a rough few years. Not long after the London summer games in 2012 and his subsequent retirement, an image surfaced of Phelps smoking from a bong, and, not long after, he got a DUI—his second in a decade.

ESPN’s E60 recently made a short documentary about the period in Phelps’ life (just a heads up, it contains some censored strong language). As Phelps describes it, he actually became suicidal, believing his reputation was ruined and that he was prone to making major mistakes. But, after hearing from fellow athlete Ray Lewis—who, himself has comeback after facing serious legal troubles—Phelps decided to get his life back on track.

The story has some interesting moments, including Phelps reconciling with his parents and going to a behavioral rehab facility, but, one of the most notable elements is the role that Rick Warren’s The Purpose Driven Life had in his comeback. Lewis gave him the best-selling Christian book, which turned his life around.

He explained:

It’s turned me into believing there is a power greater than myself and there is a purpose for me on this planet … It helped me when I was in a place where I needed the most help.

Lewis said that shortly after giving him the book, Phelps called him and said, “Man this book is crazy! The thing that’s going on…oh my gosh…my brain! I can’t thank you freaking enough, man. You saved my life.”

Not only did it help him restore the strained relationship with his father, but it’s also helped him on a road to a comeback: This year, Phelps returns to the Olympics as the most successful American athlete of all time.