The reasons for such shifts vary, they say: an employer downsizes, a spouse's job moves across country, more money is needed, or an individual strikes out in pursuit of a long-held dream.
Whatever the case, there are ways to smooth the path to transition, experts say, and avoid ending up in the same spot you're trying to leave behind.
Dr. Timothy Butler, a senior fellow and director of career development programs at the Harvard Business School in Boston, said it's essential to conduct a deeper self-assessment before changing careers.
"Do you truly understand your situation? Maybe it's all about career and maybe you do need to change jobs, but not necessarily. Take a look at what the issues really are. The relationship with your boss? The culture of your organization? Maybe that's not right, but functionally what you're doing is just fine," Butler said.
Butler suggests individuals take a multi-step approach to self-assessment before launching into a new career. That approach involves experiencing self-doubt, working with your inner critic, dropping your old way of thinking and developing a new imagination, and recognizing patterns in your life, such as recurring interests or social needs.
"This is the process you need to work through before you go into career transition. At that point you have a deep understanding of what it is you are looking for. And then you search for it," he said. Butler also delves into these issues in his new book, "Getting Unstuck: How Dead Ends Become New Paths."
The need for self-assessment also is touted by C.J. Liu, a certified life coach, in her "three key components" to planning for major career shifts. Liu says you should first gain clarity by getting to know yourself: what you like, what you're good at, what makes you feel successful. Once that's crystallized, you should explore all possible avenues by networking and investigating careers that pique your interest. And then, she said, you make a career plan, taking into account your financial, health and family obligations.
Anna Ivey, a career counselor, said it's important to give an employer at least one full year before moving on. Once you decide to move on, she said, try giving yourself a substantial amount of time - six months is optimal - to do research, particularly through networking and informational interviews.
"It is so important to talk to people doing what you think you want to go into. Nine times out of 10, it's not quite what you envisioned," Ivey said. "Ideally, people will be very candid and tell you the truth. If they're honest, there will be great intelligence to gather."
Dr. Howard Seidel, a partner at Essex Partners in Boston, a company that specializes in senior executive career transition, agreed that it's vital to investigate your options before making a change. For example, if you're interested in consulting, try doing a little of it on the side, he said.
There are risks involved in career change, Seidel said, and it's important to evaluate them - but equal risks loom if you don't make a change. "What happens if you have to make the change five years from now?"
Seidel and Ivey both said they've seen career-changers meet with success. Ivey mentioned one woman who went from being a graphic designer to doing art therapy for troubled children.
"It was so interesting because she didn't do a 180 [change] away - she leveraged the training and contacts and network she developed and just repositioned all the great things she built up," Ivey said. "I think you find a lot of successful career changers building on what they've done before so that all the capital they've built up doesn't go to waste."