Why can you keep up with passive investing? The reason you can 'believe in 15 years from now'
Last updated: November 2026 | This article was written when I had only been investing for a few months. I will add to this article as I experience market crashes and milestones.
What does it mean to “believe in 15 years” with index fund investing?
“Set up your automatic investments and forget about them. Then, believe that they will be up in 15 years.”
This is a phrase often heard as a golden rule of passive investing, but it makes me wonder.
Actually, when I first started investing, I opened my brokerage app multiple times a day.
With a groggy head after a night shift, I would see my portfolio value drop by a few thousand yen and feel a sense of panic.
“Forgetting” and “believing” are similar, yet different. That is where this article began.
What does it actually mean to “believe”?
Is it just praying to the gods or holding onto a faint wish that things will grow?
Or is it desperately trying to convince yourself while being terrified by news of a market crash?
Now at 47, while protecting my life with my family and continuing index investing, I feel like I have gradually begun to see the true nature of this “belief.”
In conclusion, for me, “believing” in investing is not about groundless prayer.
It is a conviction in the overwhelming fact that “billions of people around the world are working hard every single day.”
The reason I realized “the global economy will continue to grow” on my morning commute
My daily life is ordinary, just like anyone else’s.
On my way to a shift-work job, or during the quiet time after sending my children off to school.
When I look around, there are “people working” as a matter of course.
Supermarket clerks opening shutters early in the morning.
Office workers looking at documents on their phones with serious expressions on a crowded train.
Construction workers calling out to each other in the scorching heat or cold wind.
Engineers continuing to write code in offices lit up late at night.
Everyone gets out of bed and heads to work every day, for themselves, for their families, or out of a sincere desire to have a slightly better life than they do now.
Without being forced by anyone, billions of people around the world are working hard and using their ingenuity in their respective roles, today and tomorrow, without rest.
When I imagined this scene, a conviction was born.
“With this many people working desperately every day, there is no way society won’t evolve or grow.”
On the morning after a night shift, the people I pass on my way home are the ones heading to work.
I am at the end of my day, and they are at the beginning of theirs.
Yet, in the same society, delivery trucks are unloading in front of convenience stores, and the station bakery is lining up fresh bread.
Being able to see this “staggered day and night scenery” might be my own small advantage.
The essence of index investing | Investing in “people working around the world,” not just stock certificates
In the world of investing, difficult terms like “capitalist growth” or “the upward trend of the past 100 years” are often used.
But behind those numbers, everything is human activity.
Technological evolution: The ingenuity of wanting to make things “more convenient” creates new products and services.
Improvement of life: The desire to “give my children a good education” or “eat delicious food” creates demand and drives the economy.
Overcoming challenges: Even when pandemics or recessions come, companies restructure to survive and create new ways of working for a new era.
As long as the global population grows and each individual continues to move forward with the desire to “live better,” the total value of the world will inevitably expand.
When we buy index funds and set up automatic investments to leave them alone, we are not simply “buying stock certificates.”
We are entrusting our assets to the “baton relay of billions of people working around the world.”
Why I don’t “panic sell” even if a crash happens during my 15-year long-term investment
15 years is by no means a short time.
15 years ago, I was working in the food service industry, struggling with raising children and managing the household budget.
If I had told my past self, “15 years from now, you’ll be making these monthly investments,” I don’t think I would have believed it.
Therefore, “believing in 15 years” is also a small promise that the current me is making to my future self.
My children, who are currently in middle school, high school, or college, will be in their 30s in 15 years and should be walking through society on their own feet.
I myself will be over 60, reaching a major milestone in life.
During those long years, there will undoubtedly be years of market crashes. There will surely be days when the news screams about the “return of the Great Depression” and asset values drop significantly.
But that is exactly when I want to remember.
Even if the stock price screen turns bright red (a major crash), on that day, factories around the world will still be running, delivery trucks will be driving, and smiling clerks will be standing at convenience store registers.
There is no need to be swayed by the “stormy waves” on the surface of the market.
The reason I can stay calm during a crash is that I hold 1 million yen in cash as an emergency fund, separate from my investments.
Anxiety does not disappear with just a “belief.” I believe that only with a system and preparation can one truly believe.
If you believe in the “huge current of the world moving forward” that flows deep beneath the surface, you won’t panic and sell (panic sell) along the way.
The biggest benefit of leaving your investment settings alone is reclaiming “your own daily life”
The biggest benefit of “setting up your investments and forgetting them” is being freed from money worries and being able to focus on the “important life right in front of you.”
Spending time glued to daily stock charts, feeling happy or sad, is too much of a waste of life.
The warmth of dinner time with the family.
Casual conversations at the gym I always go to with my wife.
The rich time spent turning pages of a book in a quiet cafe on a day off.
The sense of accomplishment from working steadily on my own job and sharing results with colleagues.
The true purpose of asset formation should not be just increasing money, but nurturing these “non-positional goods” (mental and physical health, free time, family bonds).
Once you have created a “system” for automatic investing, you can leave the rest to the machine.
While we forget about our investments, we should live our “today” right in front of us to the fullest.
“Common Questions”
Q. Is it really okay to leave index fund investments alone?
A. I ensure I have an emergency fund and then only check my balance once a month.
Q. Is there a guarantee that it will be up in 15 years?
A. There is no guarantee. That is why I don’t think “it will definitely go up,” but rather “by continuing for a long time, I increase the possibility of being rewarded.”
Q. Should I stop investing if there is a market crash?
A. In our household, we have a rule not to stop. It is a time when you can buy cheaply, and I feel it is harder to judge the timing to stop on my own.
Summary: What you can do starting today for asset formation 15 years from now
In investing, “believing” is not about closing your eyes and praying for a miracle.
It is about quietly reflecting on the fact that “somewhere in the world today, someone is working to make society better” and entrusting yourself to the accumulation of those efforts.
Just as a tree in an orchard bears rich fruit 15 years later.
While we carefully manage our daily lives, I want to wait patiently and look forward to seeing the giant tree that is the global economy grow.
Now, once you’ve checked your investment settings for today, let’s put down our phones and return to our work and lives.
Because our fellow workers around the world are moving the earth forward again today.
Today, just check the amount of your investment settings and close the app. That is enough.
2 Recommended Books for Successful Passive Investing
Here are some recommended books that will help you delve deeper into and logically support the “passive investing mindset” and “how to approach money and life” mentioned in this article.
1. For those who want to eliminate investment hesitation and create a system
“The Passive Investing Technique” (Hajime Yamazaki, Kenichi Minase)
This is a masterpiece that teaches the golden rule of why you should just “leave” index investments alone without being swayed by daily price fluctuations, in the simplest way possible. It is a bible for those who want to make investing a part of their life and focus on their own daily routine.
2. For those who want to understand through data why long-term investing pays off
“Just Keep Buying: Proven ways to fuel your growth and build wealth” (Nick Maggiulli / Diamond Inc.)
A book that proves the structure of “the labor and growth of people around the world” with vast amounts of data and overwhelming persuasiveness. It allows you to logically understand the correctness of “keep buying and then forget about it.”
*Links to books and other items introduced in this article include affiliate links such as Amazon Associates.