If you want to become a millionaire or multimillionaire -- and who doesn't? -- there are many things you can do. For example, Fidelity Investments, which administers millions of 401(k) accounts for companies, has named many wealth-building habits of its account holders who have amassed a million dollars or more -- such as contributing at least 10% to 15% of your salary to your 401(k) regularly. (Note that, for many people, 10% isn't enough.)

Here's a look at many secrets of IRA millionaires -- one kind of obvious one and eight not-so-obvious ones. Lots of them apply if you're working toward a million dollars (or more!) in a 401(k) and/or a regular, taxable brokerage account, too.

The kind-of-obvious secret of IRA millionaires

Let's start with the kind-of-obvious secret of IRA millionaires. (We'll get to less-obvious ones soon.) To amass a million dollars or more in a fairly reliable manner, you'll want to save and invest meaningful sums regularly. The table below offers great examples, showing how much you might amass over time if you average 8% annually:

With enough time, you can probably reach a million dollars or more -- and you'll get there even faster if you can sock away even larger sums than in the table above -- perhaps in other retirement accounts, or in your IRA as contribution limits increase over time.

With enough time, you can probably reach a million dollars or more -- and you'll get there even faster if you can sock away even larger sums than in the table above.

Meanwhile, you also need to invest that money effectively -- i.e., don't just park it in a savings account (even the best savings account) or load up on penny stocks with it. A good low-fee index fund, such as one that tracks the S&P 500, can be all you need to build a comfortable retirement.

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Over many decades, the S&P 500 has averaged annual returns close to 10%, but it might deliver somewhat more or less over your investing period. Here's what a difference your growth rate makes:

Here's what a difference your growth rate makes, if you're socking away $7,000 annually:

Eight not-so-obvious secrets of IRA millionaires

It's clear that those who have amassed a million dollars or more have probably been socking away a lot of money frequently -- for a long time. It should be clear that it's a smart path to greater wealth for you, too. But there's another category of secret to uncover: Just how you get all that money to invest. After all, your income is probably fairly limited, right?

Well, here are some things that many wealthy people have done:

1. Don't assume your income is limited to your salary. Look into side gigs that you might take on for a short or long while. Look into how you might qualify yourself for better-paying jobs.
2. Get out of debt as soon as you can. It's hard to get ahead if you're paying 15% or 25% in interest while aiming to earn 8% or 10% on investments.
3. Have a budget. It can help to know where your dollars are going and direct them where you want them to go -- such as into retirement savings accounts such as IRAs or 401(k)s.
4. Live below your means. When you walk around with credit cards in your pocket or pocketbook, it's very easy to just charge, charge, charge. Don't do that -- and leave your card at home if the temptation is too much. Aim to only buy what you really need.
5. Don't try to keep up with others. Sure, your neighbor might have a snazzy car that you'd love to own, too, but for all you know, said neighbor might be up to his eyeballs in debt. Keep your cars for many years, if possible. Remember that every dollar you spend now is a dollar that might have been put to work growing for you for 10, 20, or even 30 years.
6. Seek and use discounts, coupon codes, and sales events. Why pay more than you need to?
7. Make it like a game. All this saving can be more fun if you try to challenge yourself in a satisfying way -- such as setting a spending limit at the supermarket and working hard to remain within it. (You might even pick a spending limit for the week out of a hat, to make it more of a fun challenge.)
8. Delay retirement. This isn't an appealing move, but it can be powerful, allowing you to add some last thousands or tens of thousands or more to your nest egg.

If you can act on some or all of the tips and secrets above, you can greatly improve your financial health and your future financial security.

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