When does a midlife crisis start?

When I was in my twenties, I thought I was in a midlife crisis, but it turned out to be a career crisis -- I was not happy in my job but was living in an age when people simply just did not change careers often.

Then when I was in my thirties, I thought I was in another midlife crisis. Figuring I would live to 65 or 70 years old, it seemed logical that I would have my crisis mid-way through. So I pursued my entrepreneurial dreams with the idea that I would glide into retirement.

Then, I sold my business and was faced with the fact that I was nowhere close to retiring. Now in my forties, I realize I needed yet another career move but had to consider that the best years of my life might be behind me.

Well, it turns out, science thinks I may just be getting started. Thank you, science.

As recently reported in Quartz by reporter Corinne Purtill, psychologist Laura Carstensen, the founding director of the Stanford Center on Longevity, thinks we should be starting our full-time careers when we turn 40.

According to Carstensen, the current career path many have followed for decades -- going to school and starting a career in our twenties -- is no longer realistic, as it fails to take into consideration our changing cultural norms and increased demand on our time.

"People are working full-time at the same time they're raising children," states Carstensen. "You never get a break. You never get to step out. You never get to refresh. We go at this unsustainable pace, and then pull the plug."

She believes, therefore, that it is time to rethink the career expectations.

Is the idea of starting our career in our forties even logical?

It is if you consider that we may not have reached our maximum age potential, which was the findings of a new study published this week in the journal Science.

The study looked at 3,836 elderly locals in Acciaroli, a small town in southern Italy, where about one-in-60 residents are over 90 years old. It found that as the residents aged, the death rate seemed to stop rising. I did, in fact, plateau at around 105.

According to one of the study's authors, Elisabetta Barbi, a demographer at the University of Rome, "If there's a fixed biological limit, we are not close to it." Therefore, as health awareness and medicine continue to advance, so too will our age limits.

The science behind the findings is still under review and is not without its detractors. As Siegfried Hekimi, a biologist at McGill University, states, "This is a reasonable theory for which there is no proof." He does, however, admit, "We can find out if there is."

Regardless, if we are living longer (fact) and changing careers more often (my non-scientific observation), then why are we stressing about maximizing our career by the time we reach 65 -- when we may have reached only a third of our potential?

This old model could also turn out to be detrimental. If we suddenly stop working at the age of 66, the current retirement age to collect social security -- which many experts think may soon be bankrupt -- and retire, it just is not practical to sit on the porch swing for another 30 or 40 years.

More importantly, also may not be healthy psychologically.

According to Carstensen, individuals should focus on the long-term marathon that our careers are turning into and plan for a long career with breaks along the journey. Under this new attitude, full-time careers would start around the age of 40 and would be longer, possibly retiring around the age of 80.

And if you think you are too old to start a new career, think again. Research indicates that you are never too old to learn new skills, and there is no shortage of resources if you are willing to try. Moreover, some research shows that the ideal age for a startup entrepreneur is 40.

Rejoice, for there is still hope for midlife crisis career-changers -- like me.

And if we are all living longer, we can look forward to more experiences as well. Consider Myda Lewis, a resident at Westhaven Nursing Home in Stillwater, Oklahoma, who recently was prepared to celebrate her 107th birthday. She mentioned to the employees that she had always wanted to be in a parade.

So, the employees gave her a town parade.

Happy birthday, Myda, and salute!

What do you think? Are you starting or re-starting your career in your forties? Please share your experience and thoughts below with others.