Because of our negativity biases among other factors, we tend to make assumptions when we do not know something. This quite often results in a lot of anxiety. You might be talking to a new person and he looks away and you quickly make up a story about how he does not not like you. You may see a new mole on your arm and quickly make up the story that includes you having cancer. You may leave a job interview and not receive a call back the next day and assume that you did not get the job. Guess what, all humans practice these anxiety promoting assumptions at varying degrees. However, if you practice being aware and accepting the reality that your thoughts do not make things true, you begin a healthy practice of cohesion between psyche and reality. End result = less assuming = less anxiety.
“When we believe in lies, we cannot see the truth, so we make thousands of assumptions and we take them as truth. One of the biggest assumptions we make is that the lies we believe are the truth!”
~Don Miguel Ruiz