Imagine placing a slice of lemon in your mouth. As you think of sucking the fresh sour juice from it, you’re probably noticing an increase in your saliva. There is no actual lemon and you’re not really sucking on a fruit, yet your mind and body react as if you are. How is this possible?

Our mind doesn’t know the difference between what we are actually experiencing and what we are imagining.

It is the same when we imagine something negative. If you think about how terrible it would be to lose your job, for example, the mind sends a “threat “ signal to our brain, which activates our fight or flight response. We would experience the physiological symptoms of stress and anxiety — rapid heartbeat, sweaty palms, higher blood pressure, etc. — even though it never actually happened. And if the imagined negativity continues, it can lead to chronic anxiety, panic attacks and even phobias.

Alternatively, when we imagine positivity — scenarios of love and kindness — our mind sends a message to our brain that life is good and we are safe. This fosters joy, calmness and even success, ultimately improving our mood and bettering our lives. It’s a no-brainer then to see how thinking positive thoughts can attract more positivity in our lives.

We understand this intellectually, but why do so many of us struggle to do this experientially?

Our minds are wired to focus on negativity because evolutionarily speaking, that is what can potentially threaten our survival. Our amygdala, the part of the brain that focuses on physical survival, demands that we watch out for negativity. When we were walking in the jungle or open plane, we needed to remain alert to anything unusually negative to survive; missing the sight or sound of a predator could prove fatal.

However, this alertness doesn’t always serve us in our day-to-day lives. For example, going on a date and harboring anxious thoughts about how badly you were treated by an ex-partner could set up the date for failure. There is a likelihood that you may misinterpret innocent words or actions based on a negative past experience, identifying your current partner as a “predator.”

We need to rewire our brain so that we can let go of behaviors that were once needed to survive, but now prevent us from moving forward.

Mindfulness and meditation can help us in a simple but profound way. Along with its calming benefits, meditation can help us stay in the present moment. We awaken to the reality of how well and safe we actually are in this moment. We need to cultivate this way of thinking so the reality of the moment outweighs the illusions of fear from the past or about the future.

We can then use imagination to our benefit; experiencing joy, calmness and success the same way we “tasted” that sour lemon.

This article was originally published on HuffPost on July 20, 2016.