If you're over the age of 35, you may have learned early in your career that frequent job-hopping looks terrible on your resume. As someone who did leave jobs every couple of years until I became self-employed, I was told that the frequency that I went through jobs showed a lack of commitment to the companies I worked for. A great worker, I was told, was someone who stayed with a company as long as possible, showing loyalty and commitment that was repaid with a pension plan and a retirement party.

That idea has changed — and many younger workers never learned it to begin with. Now, moving around frequently isn't looked down upon; it might even be preferable. (Obviously, this idea isn't apropos to every career — academia and medicine are two obvious exceptions — but it applies to many.)

It's about learning

Why three years? As the video above explains, acquisition of new skills slows down after that time period, and it benefits most companies to have people in a job who are excited about and have passion for their work — which usually goes hand-in-hand with doing new types of work or acquiring new skills. After a few years, even the most motivated people have been doing their job for long enough that they're not learning as much as they would if they changed jobs.

Think about it: While it can be stressful to start a new job, it's also exciting. There are new skills to master, new people to interact with, and new opportunities to use your existing skills, and maybe even expand the repertoire of things you can put on your resume. All of that passion and energy is obvious to your employer, and it makes you more valuable.

Lest you think that all this job movement benefits employers to the detriment of employees, blogger Penelope Trunk says that changing jobs regularly can be more stable than you might think, because it leaves the ability to move to a better position in the worker's hands, which is empowering.

“In terms of managing your own career, if you don’t change jobs every three years, you don’t develop the skills of getting a job quickly, so then you don’t have any career stability,” Trunk told Fast Company. “You’re just completely dependent on the place that you work."

You're also likely to earn more money if you move around: "Staying employed at the same company for over two years on average is going to make you earn less over your lifetime by about 50 percent or more," writes Cameron Keng on Forbes.com. Part of that is due to the fact that regular raises, which used to be about 5 percent annually, have disappeared (or are much lower than 5 percent) — so you're not going to see much extra money year-over-year unless you move around. Most people see a raise when they get a new job since they are looking to learn and grow in a new position and will apply for the next job slot above them — which is what you should be doing when you move. All of that should result in being paid more when you switch it up.

Also of benefit to the worker is that you'll probably develop more skills, and do so faster, when you move around on a regular basis. So all that work finding a new position (and let's not kid ourselves; it's quite a bit of work when you're job searching) can and will benefit you, too. And as Cenk Uyger said in the Young Turks video clip above, sometimes you can get "typecast" in the job you started in —i f you start at a lower level in a company, you might always been seen that way by your coworkers. Moving on once you've moved up puts you in a different light with the new people you work with.

But it's also about personal circumstances

Young mother teaches daughter to read Kids learn new skills every day. What about you? And remember, you don't have to rely on your job for new learning experiences if that's the best job for you at this stage in life. (Photo: NinaViktoria/Shutterstock)

Just because the way we move through life and jobs (and careers) over a lifetime has changed with the millennial generation, doesn't mean this idea doesn't apply to other age groups. People at almost any stage of their career can benefit from moving around — and for older workers, it may be of even greater utility, since it keeps your skills and talent relevant to the market.

Again, this really depends on the job you have and your life circumstances. Some people need to stay in a certain city or town that may have limited room for movement in their field so they can care for family members or keep their kids in school until a certain date. There's more to life than how much you earn and what job you do; how your job affects the rest of your life matters, too.

You should always take career advice like this with a grain of salt. If you like your work and are being challenged and are regularly engaging in new tasks, expanding your skills and contributing greater value to your employer, then that's fantastic and you shouldn't walk away for the sake of simply trying something new. But you can at least use the three-year mark to assess if you are indeed learning and growing and to ensure you aren't getting stale or too comfortable in your current role.

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.