As Hollywood actress Reese Witherspoon prepares to star in the true story of a woman who embarked on a gruelling solo 1,100-mile hike through the wilds of America, the real-life heroine Cheryl Strayed reveals in a new book how terrible grief fuelled the challenge.
Wild charts her journey from the Mojave Desert to Washington state, during which she faced rattlesnakes, black bears and the threat of mountain lions.
Today, Strayed, 44, is a full-time writer. But a lifetime ago, when she was 26, separated from the husband she loved and shooting heroin with a new boyfriend she didn't, she made the most impulsive decision of her life: to take a three-month 1,100-mile solo hike along the Pacific Crest Trail – from the Mojave Desert through California and Oregon to Washington state.
But this is no travelogue. Four years earlier her beloved mother Barbara, known as Bobbi, had died from lung cancer aged 45. The trauma of that loss scattered the family, and Strayed's world spiralled into self-destruction.
"I cried my heart out while I was writing those chapters," she says of the sections which charted her mother's death, from the shock of the diagnosis to the final morphine-ridden end 49 days later. Strayed was 22 at the time.
A week later, she was unfaithful to her husband and, over the next few years, her marriage collapsed and her life went into meltdown. She ended up in an on-off relationship with a drug user called Joe.
"I had reached rock-bottom. I knew that this was not what I was meant to be doing. I was throwing my life down the drain. I was depressed and during that time I remember waking up in such despair. I remember thinking, if I continue to feel this way I'm not going to live."
She had no hiking experience. In the initial stages, her feet blistered, toenails fell off and her hips were rubbed raw from the straps holding up her oversized backpack.
"I would sometimes have the most gruelling, exhausting, terrible day and then I would sit there eating my little pot of dehydrated food looking across the most amazing land, with nothing in sight but the many colours of the wild, and just have this sense of how fortunate I was to be there at that moment and also that I'd gotten there on my own strengths.
"If I thought, I've still got 17 miles to go today before I'm done, I would despair. I'd try and think – it's a mile to that creek, where I'll stop for my chocolate bar. I had to make the goals small and the rewards many.
"I'd set out to hike the trail so that I could reflect upon my life, to think about everything that had broken me, and make myself whole again. But the truth was, at least so far, I was consumed only with my most immediate and physical suffering. Since I'd begun hiking, the struggles of my life had only fluttered occasionally through my mind."
Some 18 years later, Hollywood star Reese Witherspoon has bought the film rights and Nick Hornby is now writing the screenplay. As producer, Strayed will be a consultant on the movie.
"Reese was the first person to read it in Hollywood. She was looking for books featuring strong women.
"An experience like that is empowering. I used to get so much affirmation from things that don't really matter, like how I look and my sexual appeal. Here I was, fully involved in this physical and psychological thing, which gave me a deeper sense of self-worth."
Wild: A Journey From Lost To Found by Cheryl Strayed. Publisher: Atlantic Books, £12.99.