Editor's note: The market hasn't been easy on investors these past couple years.

Then again, it hasn't been an easy couple years in general. Investors have had to deal with a high-inflationary environment, ongoing global tensions, and more recently, banking fears. But sometimes, we're our own worst enemy when it comes to investing...

In today's Masters Series, adapted from the January issue of our Retirement Millionaire newsletter, editor Dr. David "Doc" Eifrig details how decision-making is crucial to being a better investor. By doing your own due diligence, you'll have a better chance of surviving the market than those who follow the herd.

Do Your Homework and Don't Run With the Herd

By Doc Eifrig, editor, Retirement Millionaire

I'm not as smart as I used to be. You probably aren't, either.

You see, human cognitive capacity peaks somewhere between 20 and 30 years of age.

Now, this doesn't mean that your mental life runs downhill after 30... far from it.

Only a specific facet of intelligence declines once you reach that age.

Based on ongoing research, raw processing power seems to peak just before 20... short-term memory improves until 25 and starts declining at 35... and vocabulary grows until late in life.

You can improve your thinking in many other ways through thought and experience.

So maybe we're not as sharp as we used to be... but we can certainly be wiser.

In this pursuit of becoming wiser, my decadeslong investment career has served me well. Because to me, investing isn't really about making money. It's about developing a feel for the moment and making careful decisions.

When it comes down to it, investing is decision-making.

Fast calculations and mental acuity may help certain forms of trading. But for long-term investors, the true measure of success is slow and deliberate decision-making.

Better investments don't come from learning new accounting tricks or discovering some secret indicator. Not even the best rhyme or mnemonic will help you memorize your way to greater wealth.

Investing is about how you collect information, how you squeeze it into your brain, and what sorts of rational and valuable decisions you can make given the mental abilities we all have.

Becoming a better decision-maker helps you in all aspects of your life – and especially in your investing.

But it's not as easy as it might sound...

Your brain is always trying to trick you... all the time. Our thinking processes are full of little biases and broken connections that lead us to erroneous decisions by taking shortcuts rather than reasoning things out.

In fact, there are three behavioral biases that lead people to make poor decisions about their money and their investing: loss aversion, the endowment effect, and the backfire effect.

But people make more than three mistakes when it comes to money. And my goal is to help you correct them.

None of us can totally break free of these biases. They're deep within our brains. But if we're aware of our weaknesses and work to overcome them... we can all get better and better at it.

By understanding how your mind is structured and what it might try to do to you, you'll be in place for not only a stronger investment account... but also a better life.

Knowing how your brain works can also help you avoid running with the heard.

When individuals don't follow the crowd, their amygdalae start firing. This makes them feel nervous... even sick to their stomach. So basically, our instincts work against us in the markets.

Following the herd can cause investors to buy at the top, when everyone else is buying... or sell at the bottom, when everyone else is dumping their stocks. And sometimes, there can be serious consequences for buying or selling with the masses.

So even though your brain is wired to follow the herd, fight this urge. Flip the way your brain wants to work.

As a general rule in investing, you need to do the opposite of the herd.

This contrarian mindset takes courage. But being a contrarian when investors are scared often leads to massive gains. And we're seeing some fear today.

Markets never go up in a straight line. There's still plenty of uncertainty surrounding the economy and the global political situation. So it's always smart to be cautious, especially where we see too much "hype" in certain trends.

So, in investing and in life, wait a tick before following the herd. The impulse to run is there, but take your time and think before you act.

Here's to our health, wealth, and a great retirement,

Doc Eifrig

Editor's note: Doc is a big believer in health care. And right now, we're in the early days of multiple converging health care breakthroughs...

Doc believes his colleague Thomas Carroll – senior analyst of Prosperity Investor – just uncovered one of the biggest growth stories of the decade. One company in a small corner of the health market could soar 842%. Hundreds of billions of dollars could move on this announcement... So make sure you learn the details now. Get the full story here.