It’s too often said – and I’ve been guilty of contributing to this myth – that the only realistic way to become wealthy is to go into business for yourself.

While it’s true that reaching billionaire status is almost always the result of owning large blocks of stock in a business you own and run, you can certainly become a millionaire and even a multimillionaire as an employee. I know that to be true from personal experience.

Even an ordinary employee can become wealthy simply by earning a decent income and saving a good portion of it.

Consider this: If you can save $10,000 a year over an average career length of 40 years and invest it in a stock portfolio earning an unexemplary 9% ROI, you will retire with a net worth of $3.3 million.

Does $10,000 a year sound like too much? Does $6,000 a year – $500 a month – sound more doable?

That will give you a retirement nest egg of $2.2 million. Not bad, right?

And there are ways to do much better than that, which  I’ll get to in a minute.

Here’s the thing: The secret to getting rich as an employee is to save as aggressively as you can while you nudge up your yearly compensation.

There are 4 simple ways to gradually increase your income:

1. Shine immediately. Show your supervisor, from day one, that you are smart, ambitious, loyal, and talented. Make it clear to him that you are going to work your ass off to help him accomplish his goals.
2. Be the guy everyone wants to work with. Make your fellow employees – as well as the big bosses – feel like you are someone that can get the right things done… in the right way… with a positive attitude.
3. Embrace the dawn. Never be late. As Jeffrey J. Fox observed, “Arriving to work late signals you don’t like your job very much. Even if you prefer to come in late and stay late, staying late sends the signal that you can’t keep up or your personal life is poor.”
4. Understand the most important facts about business. The lifeblood of business is profit. And the long-term success of any business depends on creating continuous value for its customers.

Do these four things and you will become known as (because it will be true) an exceptional employee. Your superiors will trust you to show up and do good work, all the while aiming to make their jobs easier and the company’s profits higher. You will be given regular opportunities to take on more challenging work. Accept those challenges and you’ll have no problem earning enough to save $6,000 to $10,000 a year.

If your idea of “rich” is more than several million dollars, you can do that too as an employee. You merely have to upgrade your reputation from exceptional to invaluable.

What is an invaluable employee?

To a business, an invaluable employee is one that can make a critical contribution to the bottom line. All businesses need various skills and talents. But they mostly need, and mostly value, those that stimulate sales, increase customer retention, boost customer spending, and bring in a bigger profit. That includes:

* the profit makers – the CEOs, division heads, and profit center managers

* those that I call the inventors – employees that are responsible for developing successful new products and services

* those that generate revenue – i.e., employees with the marketing and selling jobs conduct your own investigation into your company’s sales and marketing programs. Talk to those who already have the kind of job you want. Ask questions. Show interest. Be thankful.

Volunteer to help them in your spare time. Be frank about your motivation: You don’t want to take their jobs, but you do want to learn how to do what they do so you can become more valuable to the business.

While you are doing that, make sure you get noticed by the higher-ups in the company. Don’t boast about what you’re doing… but don’t be shy either.

Eventually, you will surely be offered the job you want. And when that happens, grab it.

One final thing: When it comes time to negotiate your compensation as an invaluable employee, fight modestly for an increase in your base pay and assertively for incentive bonuses based on your performance.

As you rise to more senior levels, you may even have the opportunity to take home a share of the profits you are generating. When that happens, you may one day find yourself saving not $20,000 or $30,000 or even $40,000 a year. You may get to the point where you are able to save six figures.

And when that happens, you’ll have the startling revelation that you can retire early… if you want to. But you won’t.

I recently read about a study, carried out by researchers at Yale and Oxford and published in The Lancet, that discovered that “exercise is more important to your mental health than economic status.”

It took me a moment to comprehend that. Is it a question that people are asking? Is it a question that can provide useful answers? Is it a question that you can even study in a scientific way?

As it turns out, the study was based on an electronic survey. The researchers asked 1.2 million Americans: “How many times have you felt mentally unwell in the past 30 days, for example, due to stress, depression, or emotional problems?”

The participants were also asked about their income and physical activities.

The results?

Those that exercised regularly felt bad, on average, 35 days a year. Non-active participants felt bad 53 days a year.

But also: Physically active people felt just as good as inactive people who earn around $25,000 more a year.

There are many problems here.

First, surveys about behavior and feelings are virtually worthless because people aren’t honest in answering such questions.

Second, even if they try to be honest, they cannot accurately remember their behavior and feelings over long stretches of time.

Third, in concluding that exercise creates happiness, The Lancet(which is becoming famous for publishing bad science) is conflating correlation with causality. This is probably the most common error made in understanding studies.

Let’s look at that study again…

It found that people that exercised regularly reported that they felt happy on more days than sedentary people. But that doesn’t mean – at all – that exercise is the cause of that additional perception of happiness.

You can use the same data to come to the opposite conclusion: that happier people are more likely to exercise – i.e., that feeling happy causes exercise.

There are actually dozens if not hundreds of variables that affect happiness. Exercise is just one of them. And since this study was not controlled (did not consider all the other variables, since doing so would have been impossible), what you have here is correlation, not causation.

With a correlation, you can come to whatever conclusion you want. And I believe that the researchers in this case wanted to come to a positive conclusion about exercise.

But it’s much more likely that the study proved what is common sense: that mentally healthy and happy people tend to take better care of themselves in every way.

You can also come to the opposite conclusion regarding income. That for the same cohort of people (those that don’t exercise), making more money does indeed make you happier.