When we look back at our lives, even if we're still young, there are always things we wish we'd have known earlier. For example, I wish I'd gotten into the habit of exercising when I was young so that it would be less of a struggle now.

There are financial lessons I wish I'd learned earlier, too, although I'm still grateful I learned them when I did, as learning them later would have been worse. Here, for example, are five money lessons I wish I'd learned when I was younger.

A young boy in a suit is holding a handful of cash and looking astonished, while standing in front of a bar chart showing rising sums.

Image source: Getty Images.

No. 1: You earn different rates of return in different places

This is an obvious one to many people, but for those who are just not thinking about money much at all, it may not occur to them. For example, if you're just parking any extra dollars in a savings account, you're not giving that money a chance to really grow. In fact, with interest rates as low as they've been in recent years, you're probably not even keeping up with inflation, so those dollars are losing purchasing power over time. Yikes!

Consider the table below, based on data from University of Pennsylvania professor Jeremy Siegel, who studied returns of various investments over more than 200 years:

Asset Class

Annualized Nominal Return,
1802 to 2012

Stocks

8.1%

Bonds

5.1%

Bills

4.2%

Gold

2.1%

U.S. Dollar

1.4%

Source: Stocks for the Long Run, Jeremy Siegel.

You'll probably earn a better rate of growth in a savings (or checking) account than you will from lottery tickets, but you can do much better, especially with dollars you won't need for at least five or even 10 years. That money will likely grow far faster in stocks.

No. 2: Investing successfully can be very simple

So... stocks. That might sound complicated if you don't know much about investing, like I didn't, until my mid-20s. Learning to be a great investor can indeed take a lot of time and effort, but you can do really well simply investing in a low-fee, broad market index fund, such as one that tracks the S&P 500 index. The SPDR S&P 500 ETF (NYSEMKT:SPY) is a fine option, and you can invest in it through an IRA account or in a regular, taxable brokerage account. There's a good chance that your 401(k) offers an index fund, too.

Index-fund investing is far from just settling, too, as index funds tend to outperform most mutual funds managed by financial pros. Indeed, as of the middle of 2019, the S&P 500 outperformed fully 90% of large-cap stock mutual funds over the previous 15 years, according to the folks at Standard & Poor's.

No. 3: Getting rich is possible even for ordinary people

I've written many times about ordinary people who became multimillionaires by investing -- people who worked as secretaries, janitors, teachers, and even priests. Some of them got there by living extremely frugal lives, and some were aided by having successful investors to follow.

However, if you have some time and patience, you can probably amass at least a million dollars without extreme sacrifice or extraordinary luck. Check out the table below, which shows how much can be amassed at just an 8% average annual return, if you're diligent and patient:

Growing at 8% for

$10,000 Invested Annually

$15,000 Invested Annually

$20,000 Invested Annually

5 years

$63,359

$95,039

$126,718

10 years

$156,455

$234,683

$312,910

15 years

$293,243

$439,865

$586,486

20 years

$494,229

$741,344

$988,458

25 years

$789,544

$1,184,316

$1,579,088

30 years

$1,223,459

$1,835,189

$2,446,918

35 years

$1,861,021

$2,791,532

$3,722,043

40 years

$2,797,810

$4,196,716

$5,595,621

Data source: Calculations by author.

If you're only a decade from retirement, it may be impossible to amass a million, but you can probably still greatly improve your future financial security by saving aggressively and investing effectively. And if you have kids or grandkids, you might start them off investing early, because they have an even greater chance of being able to build great wealth.

A finger is pointing to the word millionaire, against a blurry skyline at night.

Image source: Getty Images.

No. 4: Boring companies can be powerful growers

If you looked at my early investing years, you'd have seen me doing too much jumping in and out of various stocks, often chasing some high-flying exciting stock I'd just heard about. I made lots of investing mistakes.

One mistake was that I often discounted seemingly boring businesses, favoring more thrilling ones. But as I look at my portfolio now, many years later, although some dynamic companies have indeed performed well for me, plenty of relatively less-exciting ones have done as well or better.

Many people might consider Warren Buffett's company, Berkshire Hathaway, not that exciting, as two of its key businesses are insurance and energy. But over many years, I've more than quintupled my investment in that stock. My investment in American Express stock has gained in value more than sevenfold, too. Former Fool writer Morgan Housel recently noted on Twitter that Amazon.com stock surged 16-fold in the last decade, while Netflix shares increased in value 15-fold, and Domino's Pizza shares rose 27-fold.

No. 5: Pay bills online

This last lesson is a relatively minor one, but it's very satisfying: I was late to adopt the practice of paying my bills online via my bank's website and/or mobile app. I'm glad I'm doing it now, though -- not only because it's faster and easier than writing a check, but also because each time I pay a bill online, I'm not spending $0.55 for a stamp.

If you mail checks out about a dozen times per month, that's 144 times per year, and at $0.55 apiece, it amounts to almost $8 per year saved. Clearly, that sum isn't going to change your life for the better to any noticeable degree, but it's worth noting that millionaires are often people who have been living below their means, saving whenever possible, using coupons, buying items when they're on sale, and so on. So it is powerful to adopt that kind of mindset if you want to be able to save significant sums.

These financial epiphanies of mine may not all be news to you, but thinking about at least one or two of them may help you improve your financial condition.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.