Research suggests that as humans reach a new decade of their lives, they unlock an incredible ability to achieve greater things. Statistically, you are more likely to do something extreme at the end of each decade than in any other year of your life. That’s because humans intuitively set “temporal landmarks” in their minds to wipe away regrettable behavior to have a fresh new start to a fresh new decade. This notion means that you are significantly more likely to achieve something great when you’re 29 than if you are 28 or 30. Really.
Individually, 29-year-old people are about twice as likely to run a marathon as 28-year-olds or 30-year-olds. Researchers have found out that 29ers, 39ers, and so on, were measurably faster than those just a year older or younger than them. Social psychologists Adam Alter and Hal Hershfield came to this conclusion when they analyzed the participants that were registered in certain marathons .
Alter and Hershfeld call these people “nine-enders;” individuals who are in the last year of a life decade. What both of them discovered is that many of us push ourselves harder when we’re 29, 39, and 49, rather than when we are 30, 40, and 50. Seriously.
Some people achieve great things that they “didn’t even consider, at ages 28, 38, 48, and 58, [that they would],” which are things that they don’t do again once they turn 30, 40, 50, or 60. There’s something about having a nine as the second digit of our age that mentally changes something inside us. But how?
“People are more apt to evaluate their lives as a chronological decade,” Alter and Hershfield explain. This also means that you’reto go to the gym in the month following your birthday, and the reason for that is that we base our decisions on timing.
Whenever we choose to do something, we always have a preconceived notion of the “when” of that choice. When to start a project. When to take a shower. When to book that trip you’ve always wanted to experience. Timing, then, can be called a raw version of art, as it arises from decisions that are seemingly intuitive and sudden. So although you don’t change much from 28 to 29, or 38 to 39 – and so on – years old, the last year of a decade activates our instinct to discern just how short life is.
(With each new decade, the faucet opens a bit more.)
When we are in the middle of a decade, there isn’t much difference regarding how you feel towards your age. But when you become 29 or 39 or 49, just before the start of a new decade, your brain tells you, in simple words, to “wake up and do something spectacular because you’re dying.”
You can think about this idea as if it’s our personal odometer. Everyone has one, and it indicates when you’re closer to the end of the race. Due to our organizational and “decade-esque” style of viewing the duration of our lives, the odometer spikes whenever you are about to reach the start of a new ten-year period. Just like a rat, being able to sniff the cheese energizes us to go for it before it’s gone.
The motivating power of endings is one reason that deadlines are often, though not always, effective. For example, people with a gift certificate valid for three weeks are three timesto redeem it than people with the same gift certificate valid for two months. People given a —a date and time—are more likely to sign up to be organ donors than those for whom the choice is open-ended.
Despite that, there is actually a setback to this seemingly innate concept:
Alter and Hershfield also discovered that ‘the suicide rate was higher among nine-enders than among people whose ages ended in any other digit.’
But once more – why? If it makes us achieve great things, why does it precipitate people to end their lives as well? Once again, the answer lies in timing. In our inner clock. That said, nine-enders have experiences that alert them to try something new, and that something doesn’t necessarily have to be socially right:
On the extramarital-affair website Ashley Madison, nearly one in eight men were 29, 39, 49, or 59, about 18 percent higher than chance would predict. 
(“Life is too short,” the 29 nine-enders thought. “So let’s have an affair.”)
Besides, although there is no definitive study on what I’m about to say, I think that these pieces of data also have clear implications on the end of each century. I didn’t say at the end of each decade justly because there isn’t much of a change there in comparison to our age. 2009 and 2010 don’t seem much different. But 1999 and 2000 does.
As a means of explaining this, think about all the notable events that occurred in the year before a new century began. In 1898, for instance, the Spanish-American War was viciously being fought between two opposite parties. However, as soon as January 1st, 1899 began, a peace treaty between the United States and Spain was ratified by the U.S. Senate, ending the war. (It was actually signed in February).
As to 1999, the Columbine School Shooting happened, killing 13 people. In fact, Eric Harris and Dylan Klebold, the perpetrators of this atrocity, were just about to turn into nine-enders (19) when they committed this crime. The difference is that there was another “temporal landmark” in their lives that did not involve their age – the fact that they were Seniors about to graduate from Columbine. By age 19, they would have already been in college.
And the list of centuries ending in “9” goes on. There are many hidden elements in our society which are difficult to identify. However, some of these factors are easily recognizable as soon as we accept that humans are not limitless. We all die one day, so it’s logical to want to achieve something before dying. And for some people, that means running a marathon at the age of 29. Or going to visit the Great Wall of China at the age of 79. Or committing suicide at the age of 19. Or even having a psychotic eruption where you end up shooting up a high school just before your graduation.
Hopefully, I won’t need these intrinsic factors to motivate me. I am assured that I can do that on my own no matter how old I am. As for now, I feel confident that I can achieve great things by not being a nine-ender, but by aspiring to be a human being that can commit myself to the things that I feel passionate about. Even so, I really wish I can still achieve something great by the time I’m 99. Maybe then will the transition from a two-digit to a three-digit number motivate me to accomplish more.