As a culture, we love to tout the power of positive thinking. We're told to look on the bright side, focus on the good, and reach for the stars. We love a good story of dreams coming true against all odds, and from a young age we're taught that whatever we believe, we can achieve. Optimism is practically in our DNA as Americans. But on an individual level, what if this type of incessant positive thinking is exactly what's keeping us from achieving our goals?

According to New York University psychologist Gabriele Oettingen, our society's cult of optimism may not be making us much happier or more successful. In fact, Oettingen's research has found that the principles of optimism and positive thinking we so often hear aren't rooted in the latest science of motivation -- and that focusing too much on our dreams could actually backfire on us.

"Nothing is wrong with looking at the bright side, but it depends on the situation and what you'd like to do with your dreams," said Oettingen, author of Rethinking Positive Thinking: Inside The New Science Of Motivation. "Dreaming gives us pleasure and gives us the ability to mentally explore options for the future. But when it comes to actually implementing the desired future or fulfilling these dreams, then you need to be careful because just dreaming will not help you realize these things."

Instead of simply dreaming about our goals and desires, we should also envision the obstacles that could keep us from achieving those goals, said Oettingen. It's a strategy called mental contrasting, in which a desired future outcome is contrasted with the realities we currently face and may face in the pursuit of our goals.

The framework of mental contrasting can be applied to any type of goal you have -- whether it's losing weight, writing a novel, improving your relationships, or quitting smoking -- as a way to both identify your dreams and also the necessary work required to meet those goals.

In an interview with The Huffington Post, Oettingen explained some of the pitfalls of positive thinking, and how to avoid them. Here are five lessons to keep in mind as you pursue your dreams.

Dreaming can make us complacent.

Fantasizing about the future can have a relaxing effect, de-energizing us so that we don't put in the effort needed to achieve our goals. We get complacent and may not feel the need to actually go out there and do the hard work, because we are already mentally enjoying our desired outcome.

In one study, Oettingen found that people who fantasized about their goals for the week ahead felt less energized and ultimately achieved fewer of their goals than those who did not spend time fantasizing.

When we're so fixated on what it will feel like to have something done, we risk enjoying that feeling of being "already there" so much that we don't take into consideration the unglamorous, practical steps it actually takes to get there. In various studies, when Oettingen and colleagues asked people how they felt after they dreamed about achieving their goals, they reported feeling less energized, and their blood pressure was actually lower.

"If you just dream, you end up dreaming but you will not realize those dreams in actuality," said Oettingen. "You need to be aware that if you just dream along, this is not bringing you toward actually fulfilling your dreams."

When we're dreaming about the future, we tend not to imagine the things we must sacrifice and the obstacles we need to overcome to get where we want to be.

"Without anticipating these difficulties and complexities, we go unprepared," she said.

Don't separate the steps from the goal.

Becoming overly focused on achieving what you desire can lead to a sort of tunnel vision -- you can get so wrapped up in it that you don't stop to consider the necessary steps that come first.

"We need the dream... this is a good starting point," said Oettingen. "Then what we need to do is identify and imagine the obstacles that actually hinder us from fulfilling these dreams. Then we understand what we need to do to achieve these dreams."

This process of looking at what stands in the way of achieving our dreams can actually transform our dreams into behavior changes, said Oettingen.

Mental contrasting can help us link our desired outcome with the steps we must take to get there, creating a much more coherent plan for turning a dream into reality. Oettingen's WOOP system -- wish, outcome, obstacle, plan -- is a science-backed plan for success that combines the best of positive and negative thinking to help motivate us to achieve our goals.

But don't get too preoccupied with the obstacles.

While a little dose of pessimism can help you make things happen, too much negative thinking won't get you very far. Obsessing over potential bumps in the road is just about as helpful as ignoring the roadblocks altogether -- instead of feeling motivated, you're less likely to act to achieve your goals because of fear of failure.

Oettingen recommends the following process: Identify the best outcome, engage in honest self-evaluation to determine the obstacles that may arise, create if/then statements ("If [obstacle], then [solution]"). This way, you're not dwelling on either the obstacles or the outcome, but instead looking at both factors to design a plan for your future.

So if your goal is to write a screenplay in your free time, but you know that you'll struggle with procrastination, you can factor this challenge into your plan for achieving the goals. You might tell yourself, "If I find myself procrastinating, I'll download an app to block social media from my computer, and I'll set an alarm reminding me to get up early to work every day."

Mental contrasting can make us more creative.

If you're embarking on a creative project, practicing a little mental contrasting could go a long way toward motivating you to work hard and think creatively.

One of Oettingen's studies asked participants to imagine being creative. After that, Oettingen and colleagues asked them to imagine obstacles that could get in the way of their being creative. Those who identified and imagined obstacles they could actually overcome -- like not putting in enough effort or losing focus -- performed better on an ensuing creativity test than those in the control group who only imagined being creative, and those in the control group that only imagined the obstacles.

But Oettingen emphasized that mental contrasting doesn't just apply to creative work. "Everyone can apply it to their own wishes and concerns, and fill in whatever is important to them at a given moment," said Oettingen.

The most important thing is taking time for reflection.

Whether you're an optimist or a pessimist, there's no way you can achieve your goals without actually stopping to figure out what those goals really are. In our lives of constant stress, distraction and busyness, it can be difficult to find moments to pause for reflection.

Creating moments of "mental space" for yourself is crucial to thinking through your goals and creating a plan of action, said Oettingen.

"This is a daily procedure you can use for all your issues and concerns," she said. "You just need to have a little moment for yourself when you take some time to yourself -- it can be on the subway, it can be on the bus, it can be while you're taking a shower."

Simply taking time to reflect on our dreams, even without going through the entire process of mental contrasting, is still a helpful way to connect us to our most authentic dreams and desires.

"Dreaming is a vital way of claiming what belongs to you, what resonates with you on a deeper, often hidden level," said Oettingen. "It's also an effective and even critical path to discovering what isn't real for you."