Sometimes it's a self-help book which steers a dramatic career change.
But in the case of marketer turned Canberra chef and restaurateur Matt Morrissey, it was a cook book with the rather prosaic title of Cooking With Beer.
"It's curious, isn't it?," he said.
"It was that book which shaped the second part of my career because it inspired me to play around with recipes.
"If you like beer, which I do, then it made good sense to cook with it."
The book's author, Paul Mercurio, could not have anticipated the profound change his frothy recipes had on a not-so-young apprentice chef.
When they finally met and the story was told, Mercurio was both moved and inspired by the tale.
"He had never guessed [at the effect it had] but then, who would? Paul and I are mates now and speak often, which is really great."
US-born author, critic and sustainable foodie Anna Lappe once described courage as saying to yourself, "Maybe what I'm doing isn't working; maybe I should try something else".
And it takes even greater courage to make that change mid-stream in life when for most of us, a personal career trajectory is predestined, locked down by your skill-set, family and financial commitments and a host of other complications.
Morrissey began his career as a musician, veered into marketing and communications, but the sharpest turn of all occurred mid-life.
An emotional breakdown precipitated that sharp and final turn, and it was one he had never anticipated.
Born and raised in Melbourne, he signed up with the Royal Australian Navy to see the world, as so many starry-eyed young blokes do, and the recruiting slogan became his reality.
"I loved music and could play the trumpet, the French horn and the drums, so I pretty quickly found myself playing in the Navy band," he said.
"When you play, you get to travel to a lot of places and attend major events.
"I was 21 when we went to Changi prison and we heard the stories of all that courage and suffering there. I grew up a lot in that time."
In 2002, he was posted to HMAS Harman, the Naval base between Canberra and Queanbeyan, for the base's 60th anniversary and decided to settle down here. Assisting with major events coordination provided him with marketing and promotional skills, which then steered him into Defence Force recruiting.
When he left the Navy, it was into the federal public service. He took his marketing skills to Customs and Immigration (as it was then), then across to the federal police, which was where the humble public service morning tea self-catering roster metaphorically raised the oven temperature.
"Food has always interested me, and I liked to cook so we had this thing going where people brought in stuff they'd cooked for everyone to try," he said.
"Pretty soon it was getting competitive with home-made cakes, biscuits and even curries.
"I was playing around with different things in the kitchen and also that's when these TV cooking shows like Master Chef were becoming popular."
He then switched jobs to the ACT government, landing in one of the most challenging marketing and PR jobs imaginable - prisons and criminal justice.
In such robust working environments there are usually teams to share the load and support each other. But in this role, he was on his own.
"I thought I was going okay professionally for a while, but then I started to fray under the pressure; I was missing deadlines, couldn't finish things, and got really frustrated," he said.
"I should have read the signs but didn't. Then one day, emotionally I just hit the wall. I rang my boss in tears and told her I couldn't do it any more."
On the "wrong" side of 40, he made a giant leap of faith, turned off the computer and became a mature-age apprentice chef on the modest starting wage of $19.75 an hour.
But it felt like a huge weight had been lifted from his shoulders.
"I've always told my kids they should make life choices that make them happy, that they're passionate about," he said.
"So I finally listened to my own advice. And I've not regretted it."
He credits a lot of people for giving "the older bloke" a chance, including Daniel Conroy, his first supervising chef at Exchange on London, his cooking instructor at Canberra tech, Ivonne Nathan, and Bentspoke Brewing, who granted him his burning desire to cook with beer.
"I couldn't believe my luck; I landed a job working in a brewery and was finally cooking with beer!" he says.
Gaining large-group fine dining and catering experience at Lake George Winery followed on from that. Now he's taken another huge leap of faith and opened his own small restaurant, Morrissey On The Boardwalk, at Belconnen.
He's out of bed early, cooking breakfast and lunch, sourcing fresh ingredients locally and loving going to work every day. He has also published a children's cook book and become an apprenticeships ambassador.
"Some people still look down their nose at vocational training, but there's a lot to be said for 'earn as you learn' training; it certainly worked for me," he said.
He's cautious about advising people to make the profound career change he has, but believes that having a desire to do what you love and a genuine desire to learn is infectious.
"I think it comes down to your level of passion and commitment; if you commit to something and back yourself to succeed, my experience is there's good people out there who will support you," he says.