Rich Roll wasn't always one of the fittest men in the world. Far from it.
But, in falling to his lowest point he was prompted to wonder what his highest point might be.
As a 31-year-old, Roll had already recovered from a fall from grace, admitting himself into rehabilitation for three-and-a-half months for alcohol and drug abuse.
Then, as a prestigious Stanford University and Cornell Law School graduate, he had the proverbial American dream at his fingertips.
Roll found himself at age 39, cashed-up and working 90 hours a week in a law firm, but barely moving beyond his desk or the couch.
"I'd become a junk food addict and I was quite sedentary," Roll says. "I was a classic couch potato hurtling into middle age - I subsisted on McDonald's cheeseburgers and French fries and nachos and Pizza Hut pizza and Kentucky Fried Chicken and Taco Bell and that's how I ate every single day."
In the pursuit of money and status and living as he pleased, there was, he says "the implicit promise that you will be happy".
He was anything but.
"I was sort of on the cusp of realising that American 'dream' and also realising that it wasn't making me happy - it was making me quite the opposite, I was rather miserable," he recalls.
It was an existential crisis that culminated in a moment, just shy of his 40th birthday, when Roll found himself breathless and sweating with his heart beating through his chest, halfway up his staircase on the way to bed one night.
"I was on the precipice of suffering a heart attack because of the way I had been living and it really scared me," says the now-50-year-old.
"And it was a very specific, discrete moment in time when I realised that not only did I need to change how I was living but that change [needed] to be pretty immediate and pretty drastic and specific."
First Roll, admittedly prone to extremes, launched into a seven day vegetable juice "cleanse".
"It was a crazy experience because I'd never gone a single day without eating solid food and that kind of connected me with my body and allowed me to see how much I used food to medicate my emotions," he says.
"I felt terrible and couldn't move but by the seventh day I felt amazing and that's what planted the seed, y'know 'how can I feel like this all the time?' 'What can I eat that will allow me to have this energy all the time?'"
He experimented with various diets and, as a "last resort", he tried a 100 per cent plant-based diet.
"It certainly wasn't a lifestyle I was seeking out - it seemed very deprivation-oriented and I didn't align myself ideologically with the vegan movement at the time," he recalls. "I saw vegans as hippies kicking hacky sacks and following the Grateful Dead around."
But, he felt good, better than good, for the first time in a long time.
"In a week to 12 days, I felt like a teenager again - my energy levels were shooting through the roof, I just had this sense of vitality and this sense of joy and increased mental acuity, my sleep was better, my skin cleared up, like all these amazing things happened in rapid succession and that was when I realised I was really onto something... it was agreeing with me in a pretty profound way," Roll says.
"In a pretty rapid-fire way I lost a tonne of weight, I looked different, I felt different, everything in my life was starting to change," he says.
It struck him that the extraordinary can come from the ordinary.
"I became astounded by the sheer resilience of the human body - how incredibly resilient we all are when we're treated properly, how the body can bounce back, because I am a recovering alcoholic, so for years and years and years I was abusing my body with drugs and alcohol, then the sedentary lifestyle and the workoholism and the junk food diet - all these things I had thrown at my body for all these years and then, in a very short time, I felt like a different person.
"That's what led me to start thinking about human potential and my own dormant potential that I had overlooked over the years. I think that's what attracted me ultimately to the world of ultra-endurance because it's this beautiful template with which you can explore those questions."
Soon he was dusting off an old pair of runners, surprising perhaps given Roll himself acknowledges that he was "not a big runner". In fact, he says although he was a talented swimmer, the last time he had properly run was during cross country in grade seven "and I was terrible... and I never ran again".
Extraordinarily Roll's fame now comes from his athletic achievements - he finished 11th in his first ultra-endurance race, the Ultraman, a three-day, 515 kilometre race including a 10 kilometre ocean swim, a 418 kilometre cycle and a double marathon run. He went on, in later years, to become a top finisher in the same event.
"I had some success as a swimmer in high school and college but I was never a runner and certainly not a cyclist. My exploration of running and cycling in my 40s was new terrain," the father of four explains.
"But I had a want and a desire to move my body - to connect with a part of myself that was so much of who I was as a young person that I had lost touch with."
Pursuing play - and exploring his own potential - took him down an unexpected path, for moving and pushing the body is not just about physicality but a means to transcend it.
"It became a vehicle for self-discovery," says Roll, who is coming to Sydney and Melbourne in March for a talks on plant-based nutrition and achieving your potential.
"There's something about ultra-endurance... it challenges you on every plane on which you exist and it strips away everything that's false, there's no room for any mask or artifice... it connects you with who you are... how you're living your life and it forces you to ask yourself questions - 'is this the way you want to live?', 'what would you change'... The training sessions are so incredibly challenging it forces you to be in the moment... I enjoy pushing my body but it's much more than that... it's this postmodern Siddhartha's tale, the hero's journey, of trying to discover who you really are."
In the process of that discovery, Roll wrote a bestselling book, Finding Ultra, a cookbook with his wife Julie, The Plantpower Way: Whole Food Plant-Based Recipes And Guidance For The Whole Family and launched "one of the greatest podcasts of all time", The Rich Roll podcast.
But, Roll says that his ultimate discovery was that he can help others realise that change is never too late and we are all capable of more than we know.
"I found happiness by being authentically who I am," he says, "and am sharing what I've learned through that experience with others in the hope of providing people with tools and resources and information and inspiration so that they can live more authentically, so that they unlock a better, healthier more, more fully developed, more fully expressed version of themselves that I believe everyone has in them."