Why are we the way that we are? Is there anything we can do to change the way we think, behave, and react? And even if we come to know how the brain works, are we limited by our underlying circuitry or can we overcome our limitations?

Over the years, TED has put on dozens of amazing presentations that highlight the mysteries of the brain and break them down in ways that we -- laymen -- can understand. Here are the most fascinating ones we've watched and enjoyed.

The Optimism Bias

Most of us have it even if we think we don't. And even if you're a pessimist about life, it's entirely possible that you're an optimist about yourself -- maybe not in the sense that everything will go right, but in the sense that few things will go wrong.

In this TED Talk, Tali Sharot explores this phenomenon called the "optimism bias", how we're wired to be more positive than negative about our circumstances -- and how this bias can be both beneficial and dangerous.

Body Language Shapes Who You Are

"Fake it 'til you make it." It's the kind of empty platitude that no longer has any meaning because people have said it too often -- but in the context of behavior and emotions, the statement is still quite truthful.

We often think of body language as an indication of how we feel, but in this TED Talk by Amy Cuddy, what we learn is that how we feel can be influenced by our body language. You can actually change your mental state by sitting differently!

Knowing this, you'll be able to completely revolutionize your social relationships. Whether you want to be more confident or simply calm down, it's all in your body language. Fake it 'til you make it.

Our Buggy Moral Code

In this fascinating TED Talk, Dan Ariely presents his findings on the human tendency to cheat and steal. Why do we cheat and steal? More importantly, under what circumstances are we more likely to cheat and steal, or the other way around?

As it turns out, there are so many different factors that can influence us towards or away from dishonesty -- and in many cases, whether we cheat or not is heavily determined by our environment and external situation.

Honestly, this is one of the most interesting TED Talks I've ever watched. If you've ever wondered about human integrity, you owe it to yourself to play this one.

The Fiction of Memory

You can't trust your memories. Sure, when you think back on a given event or moment, you can feel confident that what you're recalling is really what happened, but as it turns out, our memories are far weaker and less accurate than we think.

In this TED Talk, Elizabeth Loftus explains how memories can be changed -- not just by ourselves every time we recall something, but our memories can be altered simply by the way someone phrases a question or statement. Scary, but true.

The Puzzle of Motivation

Do you struggle with motivation and productivity? Probably. I think we all do to some degree or another. But that raises another question: how come some people are more motivated than others? And what can you do to boost your own motivation?

In this rewarding TED Talk, Daniel Pink delves into the brain science of motivation, what damages true motivation, and what we can do to cultivate real motivation from deep within ourselves. Extrinsic motivators are outdated. We need an intrinsic push instead.

It's one of the most mind-blowing talks about human behavior ever produced by TED. The video has over 5 million views and an approval rating above 97%. It has helped so many people. Why not you, too?

Less Stuff, More Happiness

The human brain is a funny object. It tricks us into thinking that we'd be happier if we could only have this, that, or whatever else is on our radar. We buy things, even to the point of debt, yet we're still unhappy. Why is that?

This TED Talk is only six minutes long, but that's as long as it needs to be for Graham Hill to convey what he wants to say. Want to be happier? Edit your life and get rid of all the material excess. Stop chasing "things" and start pursuing "experiences".

It's one of several great TED Talks on how we should think differently about money. Money is important, but it isn't everything.

What You Know About Addiction Is Wrong

Addiction is a tough topic. It hurts to go through it and it hurts to see others go through it. And it's not just about drug addiction anymore -- many of us unknowingly suffer from tech addiction, porn addiction, and even video game addiction.

Not only that, but as technology continues to advance in unpredictable ways, who knows in what other ways we may become addicts in the future?

That's why this TED Talk by Johann Hari is so important and insightful. It turns out that addiction has less to do with chemical hooks and more to do with purpose and bonds. If you're an addict, or know someone who is, then you should definitely watch this.

The Origins of Pleasure

Despite the fact that all humans experience pleasure, we actually don't know much about it. In this TED Talk, Paul Bloom starts off with a simple question: why do we derive more pleasure from original art pieces than forgeries?

The strange truth is that pleasure is more than just about the actual experience. In fact, certain experiences can be made more or less pleasurable if your beliefs about those experiences can be manipulated.

This insightful talk sheds a lot of light on why we find pleasure in certain things and how we might be able to maximize our pleasure in those experiences.

The Pattern Behind Self-Deception

Why are human beings so likely to believe in strange and irrational things? For example: UFOs, bigfoot, ghosts, global conspiracies, etc. In a lot of ways, belief is the "default state of things" and many of us want to believe in weird things even if those things are unreasonable.

In this TED Talk, Michael Shermer explores why we tend to see things that aren't truly there and how this is rooted in two of the most basic survival skills in the human brain. Self-deception, you might call it.

Try Something New for 30 Days

It's often been said that habits can be built or broken in 21 days, but if you really want to get the most out of it, you should aim for 30 days. By trying something new for one month at a time, you can end up chipping away at your mental blocks and building up your confidence.

But remember that small changes are more sustainable, so make sure your challenges are realistic and practical. The key to success is this: the next 30 days are going to pass no matter what, so why not try something new?

If you aren't sure where to start, consider one of these money-saving 30-day challenges that will surely get your financial life in order.

On Being Wrong

We've all been wrong at one point or another, and we'll all be wrong again sometime soon. Nobody is perfect, yet we try so hard to avoid being wrong. We don't like being wrong... but why is that? Maybe there's another way to think about wrongness.

In this TED Talk, Kathryn Schulz talks about how being wrong is different from realizing that we're wrong, and that we can never know if we're wrong until that realization strikes.

A lot of times, being wrong feels like being right -- and this can be quite dangerous.

Share Your Favorite TED Talks

I know that there are dozens of other interesting presentations that deserved a spot in this article, so by no means is this meant to be an exhaustive list. But the ones we did include are so interesting that you should watch all of them at least once in your life.

Now it's your turn! If there are any other brain-related or behavior-related TED Talks that you want to mention, feel free to tell us about it in the comments below!

Image Credit: Human brain by Fer Gregory via Shutterstock