Letting Go of Negative Thinking

In the midst of being at work, reserving heavy media equipment and editing rooms for college students, I came across an article that kind of answered some lingering thoughts I'd been having lately. 
From all the weight of school, extracurricular activities, work and a social life, sometimes I have a tendency to let thoughts of doubt, worry and negativity enter my mind. Once they did however; they were hard to shake away due to the amount of stress I was going through. The nature of these thoughts were small, but I let them get so big because I kept feeding more and more attention to it. Sooner or later, I found myself in tears from all of my over-thinking. 
The back-and-forth nature of the situation had me feeling uncomfortable for a long period of time. It was time to get these insecure feelings out for good...but how?
Back to the first sentence, I was on Google tonight trying to figure out how to deal with self-worrying and cut it out of my life. Then, I stumbled upon a page that had a short, concise article that I quickly glanced over. I will not mention this article or where I got it from, but it was just what I needed in the right moment.
After reading the article plus a bunch of comments that followed, I realized that when we receive negative thoughts, it is indeed our decision whether or not to devote more time thinking about it. Our brains are great motivators for this because of the pickup of dangers or threats...we want to avoid it at all costs even if the danger or threat is not real.
Seeing as most of my negative thoughts were merely based out of nothing whatsoever, I knew I was overreacting. But how could I convince myself that those thoughts should be disregarded when I put so much of my time into the thought that it could be potentially perceived as reality?
We can all agree that negative thoughts don't feel good at all. This is due to the fact that they interrupt the cycle of life and it's mobility. No matter how true we may perceive a negative thought however; the fact of the matter is it is not truth because life does not support this thought. Whatever argument we may come up with in our heads can be invalid because it is a conflict in life's movement. If these thoughts are not based on anything factual, life does not support those thoughts.
The main point I am trying to get at is that we all want joy. I seek it with my dreams, goals, relationships, accomplishments and the little things. We all want to be in a state of joy; to match up with our desires and align them with the movement of life itself. In other words, if something makes you happy and you can seek mutual happiness that evokes a compatibility in which you both benefit and grow from, that "something" will remain in your reality. 
Once I realized it, I was speechless. I put so much time into something that was irrelevant, unreal and untruthful. The thoughts I were having were not reliable enough for me to believe them, but I did. Now I see that I can let go of these thoughts by just believing in my joy and how the things that I have in my life currently bring me joy. We just have to stop putting more time into the negative thoughts and just focus on our dreams and desires. Whatever we are dealing with in life should be based all around our personal happiness. 
And that will set you free.