The One Thing My 40-Year-Old Self Would Tell My 20-Year-Old Self

In my 20s, I was stuffing “security” into a savings account

Growing up, my family wasn’t well-off. That probably explains why I developed an awareness about money pretty early on.

In my 20s, I worked insane overtime. Watching my bank balance climb each month genuinely made me happy — not in a “look what I achieved” way, more like “okay, I can survive anything now.” Every deposit felt like adding another layer to an invisible shield around me.

It helped that my hobbies were cheap. Gaming and playing instruments cost a fraction of what golf or bar-hopping would. I wasn’t even trying to be frugal — money just piled up naturally. Looking back, that built-in low-spending lifestyle was a bigger advantage than I realized at the time.

What my grandfather passed down

The reason investing never seemed scary to me was definitely my grandfather.

He owned shares in the company he worked for and actually followed the price movements closely. “The best way to understand a company is to own its stock” — I’m not sure he said those exact words, but that’s the vibe I got from watching him.

Here’s a story my mother told me. Back in the day, my grandfather did something like proxy stock sales. Whenever the market moved, panicked clients would call him. And every time, his response was the same:

“Don’t be shaken by small price movements.”

As a kid, I had no idea what that meant. But now, as an investor myself, I realize he nailed the essence of investing in one sentence.

My grandfather and I share the same temperament, I think. When something grabs our interest, we go all in. The fact that stocks and money naturally caught my attention — that’s his influence, rooted deep. I don’t think about him every time I check my portfolio, but the fundamental mindset is ingrained.

So when I started working, I naturally bought some company stock myself. Prices went up. “Hey, this beats a savings account,” I thought. Simple as that.

I had no idea what was coming.

The dot-com crash wiped out over $10,000

Early 2000s. The bubble burst.

Losing that much money in my 20s hit hard. That was months of overtime and careful saving, gone. The security I’d built up — that invisible shield — cracked overnight. Years later, I’d lose ¥2 million on a single telecom stock — another painful lesson that knowledge and experience are two completely different things.

I didn’t make some dramatic decision to quit investing. I just… lost interest. Or more accurately, I couldn’t stand looking at it anymore. Facing the loss felt awful, so I quietly drifted away from the market.

My grandfather’s “don’t be shaken by small movements” — I’d heard it, sure. But when it’s your own money vanishing, that’s a whole different story. Funny how in moments like that, logic doesn’t matter. Emotions drive the bus.

Abenomics pulled me back in

Years passed. My savings rebuilt themselves (cheap hobbies, remember?). Meanwhile, Japan’s stock market was booming under Abenomics. Around the same time, a career setback killed my chances of a raise, which lit a fire under me to find another way to grow my money.

“Maybe I’ll give it another shot.”

But I still didn’t know about index investing. So I went back to picking individual stocks — volatile ones, naturally. Sometimes I’d make a quick profit and sell, only to watch that stock triple over the next year. The “what if I’d held” regrets piled up fast.

If you’ve ever invested in individual stocks, you know this feeling. But here’s what took me years to figure out: no matter what you do, you’ll have regrets. Sell and regret selling. Hold and regret holding. It’s endless.

The shift wasn’t “how do I avoid regret?” It was “how do I keep going despite it?” Once I accepted that regret is baked into investing, the stress dropped dramatically. That realization is ultimately what led me to stop thinking and love index funds.

The one thing I’d tell my younger self

If I could hop in a time machine and sit down with 20-year-old me, I’d say this:

“Stocks aren’t something you predict. They’re allies you collect.”

Stock prices move in ways that defy anyone’s analysis or intuition. Predicting them is a fool’s errand — professionals get it wrong constantly, so what chance do the rest of us have?

But here’s the thing. Over time, the value of cash slowly erodes. Well-run companies, though? Their stock tends to rise over the long haul. It’s almost mechanical.

So instead of buying and selling and agonizing over timing, think of it like this: every share you buy is a teammate joining your side. You’re building an army, one soldier at a time. Short-term ups and downs don’t matter when you’re playing a decades-long game. That’s the approach I eventually settled on — and I haven’t sold a single fund since 2018.

If I could give 20-year-old me a concrete action plan, it would be this: open a NISA account — Japan’s tax-advantaged investment account where all gains are completely tax-free (think of it as Japan’s Roth IRA). Then pick an index fund. A global all-country fund, an S&P 500 tracker — either works. The key is choosing something that removes your own predictions and emotions from the equation. Set up automatic monthly contributions — even $100 a month is fine — and then leave it alone. When the market drops, don’t cancel. If anything, think of it as buying at a discount. This “doing nothing” part is the hardest and most important skill in investing.

My grandfather told his clients “don’t be shaken by small movements.” That’s exactly what this means.

The long way around wasn’t wasted

The dot-com crash. Years of avoiding the market. Jumping back into individual stocks and racking up regrets. It was a long detour.

Do I wish I’d figured this out in my 20s? Absolutely. If I’d had this mindset and been dollar-cost averaging since then, the numbers would be very different today. As it stands, the first three years of index investing were painfully boring — but that boredom was exactly what I needed after years of chasing excitement.

But that’s just another version of the regret game, isn’t it? I’ll take my own advice: accept the regret, keep moving forward.

What matters isn’t when you start. It’s that you don’t stop.

What I Can Say Now

If 20-year-old me read this article, he’d probably shrug and say “yeah, whatever.” But 40-year-old me knows better. Every bit of that $10,000 loss, every anxious night checking stock prices — it all led here.

The thing that hits me hardest in my 40s is realizing that time was the single greatest weapon I had — and I barely used it. The power of compound interest makes sense on a spreadsheet, but it doesn’t truly sink in until you’ve been contributing for several years and watch the curve start bending upward. The advantage of starting young isn’t better stock-picking skills or market timing — it’s simply having more years. Even $100 a month for 20 years adds up to $24,000 in principal alone. Factor in the long-term average returns of a broad index fund, and the number on the other side is significantly larger.

Here’s the other thing: don’t be too afraid of failure. I lost over $10,000 in the dot-com crash and ran away from the market for years. But without that pain, I never would have arrived at my current approach of “don’t trust your own predictions.” Of course, it’s better not to fail. But even if you do, as long as you learn from it and adjust course, you can still end up in the right place.

The most important thing is to never leave the market permanently. Losing $10,000 didn’t end my life. Taking a five-year break from investing didn’t end my life either. What mattered was coming back — and coming back a little wiser than before.

I sometimes wonder what would have happened if I’d started dollar-cost averaging into index funds at 25 instead of 38. The numbers would be staggering. But that thought is just another flavor of the regret game, and I’ve already decided to accept regret and keep moving forward.

The “don’t be shaken” mentality my grandfather had — I took the long way around to learn it myself. Your allies? Just keep adding them, one at a time. No rush. Whether you’re 20 or 40, today is the youngest you’ll ever be.

This article reflects personal experience and is for informational purposes only — not investment advice. All investment decisions are your own responsibility.