how do i overcome negative thoughts?

Since negative thoughts drive negative feelings, the simple solution for feeling better would be to "just think positively." Clearly, this is easier said than done, or we would all be happy all of the time. While thinking more positively isn't always easy, there are two main techniques to combat negative thinking: distract and challenge. Distract, just like it sounds, is finding a coping skill to use to take your mind off of negative thoughts. The second approach is to challenge negative thoughts. Many negative thoughts are at least partially untrue or exaggerated by our anxieties, and there is a way to combat these thoughts. Some helpful ways to combat negative thoughts, are first to identify the negative thought, second to challenge the negative thought, and third to reframe the negative thought if its partially false or make a plan to cope with the negative thought if it's true. 

Note: Sometimes anxiety and/or depression leads to a spiral of swirling thoughts and feelings that makes it difficult to know how did I get here?  when you're feeling sad or angry. Oftentimes when experiencing such spirals, it can be difficult to access the rational thinking part of our brain, so this step-by-step process is better used either before or after you are experiencing heightened sadness or anxiety. In the moment when experiencing heightened sadness or anxiety, is important to use coping skills to deal with those feelings, focus on getting to a calmer state, and then consider going through these steps. The goal eventually would be to be able to go through this process and to challenge negative thoughts when you first catch them to prevent yourself from going into a spiral of anxiety or sadness, but this skill takes time and practice! 

step 2: challenge the thought(s)

The point of challenging thoughts is to decide whether the thoughts are even true or not because this will help you decide what step to take next. Keep in mind that more often than not, negative thoughts are not 100% true due to the habit for many of us to rely on cognitive distortions as the truth. Cognitive distortions are unhelpful thinking traps that many of us fall into at one point or another. Oftentimes cognitive distortions seem true, but they're at best exaggerations of reality and at worst completely untrue. Below is an infographic of some of the most common cognitive distortions. Give them a look and decide which ones you are most guilty of so that next time you find yourself falling into the trap you can recognize it. If your negative thought does not fall into one of the cognitive distortion categories, you can also ask yourself what evidence you have for and against your thought, and if you have some evidence against the thought, it's probably not 100% true. Once you decide whether your thought is true or not, move onto step 3.