Most people don’t voluntarily quit their jobs, let alone leave their professions, unless they are sitting on a pile of cash or know where their next paycheck will come from. But Jonathan Fields isn’t most people.

The Upper West Sider set aside his impressive résumé — which includes a doctorate from the Cardozo School of Law, nearly three years of experience as an attorney at the US Securities and Exchange Commission (SEC) and time on the partnership track at Debevoise & Plimpton, one of the city’s largest law firms — to start over. At what, he didn’t know.

“I was so psychologically burnt out that I knew I couldn’t make a logical decision at the time,” he says.

Fields wasn’t doing well physically, either. A few months earlier, his immune system had shut down, leaving him with an infection in the middle of his body. Luckily for him, great medical care — as well as breaking away from working long hours saturated with anxiety — restored his health. He was 31 at the time.

Much like others who experienced physical or stress-induced crises, Fields became fascinated with health and fitness. He landed a job as a trainer in a gym earning $12 an hour, where he gained expertise quickly. It didn’t take long before he excelled at the profession and teamed with a partner to open Sedona Private Fitness in Cedar Grove, NJ. Less than three years later, he sold his share of the business.

Next, Fields opened Sonic Yoga near Columbus Circle — the day before 9/11.

“New York City never had a greater need for yoga than at that time,” he says.

Around seven years later, he sold that business to focus on public speaking and writing popular books, including “Career Renegade” (Crown Business) and “Uncertainty: Turning Fear and Doubt Into Fuel for Brilliance” (Portfolio).

As successful as these endeavors were, Fields wanted to do and be more, so in 2011, he started the Good Life Project, which offers professional training, coaching, media and community to help people live more engaged, connected and vital lives.

But as you might suspect, Fields is now working on something else.

His latest venture is an app to help people discover their true calling in life via something called a Sparketype assessment. It’s currently free on the Internet in beta form, and Fields plans to reveal the business model around it later this year.

But, while continuously switching professions might appear to be the key to success and happiness for Fields, for others, it could be a prescription for a breakdown.

Consider the career track of Brooklyn-born Jerry Colonna. By the age of 25, he was the editor of popular technology magazine Information Week. At 30, he cofounded a wildly successful venture-capital firm. A few year later, he became a partner at JPMorgan Partners. He then became so severely depressed that he quit his job. He was living in Port Washington, LI, at the time.

“It was the first time since I was 13 that I was unemployed, and it scared the crap out of me,” he says. “I had no idea what I was going to do next. I didn’t have a plan.”

At times he was suicidal, and while the depression didn’t lift until 2006, the years in between weren’t wasted.

Colonna spent part of the time serving on corporate boards and consulting with nonprofits, but mostly he went to therapy, studied Buddhism and concentrated on self-inquiry.

Much of the process is detailed in Colonna’s forthcoming book, “Reboot: Leadership and the Art of Growing Up” (HarperBusiness, out June 18). It chronicles not only the journey from his earliest years to where he is today — executive coach to startup CEOs — but also includes snapshots of the radical self-inquiry through which he leads clients.

But rebooting your career isn’t always born from crisis. The seed for David Mawhinney’s Brooklyn-based children’s furniture business, Franklin + Emily, was planted when he couldn’t find a good-looking, comfortable and easy-to-keep-clean chair for his 2-year-old daughter.

“I wanted something that’s food-friendly, sourced locally, and made of sustainable materials,” he says.

see also

Should I leave my job at Google or stick it out?

I landed a job at Google and thought my career…

When Mawhinney drew a blank, he designed one and built it. Friends who saw it wanted one for their children, too. So it didn’t take long before he quit working in the city’s culinary industry to launch the business.

“I haven’t lost my passion for cooking,” says Mawhinney. And though he misses the people he worked with, he says that getting to be at home with his wife and kids when they eat dinner — and making furniture that children and parents love and that looks good in their homes — is irresistible.

The change was something Mawhinney knew he could do because, years earlier, he left a career in accounting at PricewaterhouseCoopers to become a chef.

What’s the secret? Listening to your inner voice, having the support of friends and family, and going all-in once a decision is made. It may seem risky, but not taking action is risky, too, especially if you say “no” when everything inside you says “go.”

“It’s dangerous not to listen to your heart,” Colonna says.

Click Here: