A couple years ago, I kept a negative thoughts journal. Get yourself a small notebook (something that will fit in your pocket) and write down the negative thoughts that pop into your head as they occur. You don’t need to do anything with those negative thoughts for 2–3 weeks; just get into the habit of becoming aware of them and writing them down.
Once you’ve learned how to spot your negative thoughts consistently, you need to analyze them critically. Most negative thoughts are the result of panicked “what-if?” and disaster thinking, where you take a small doubt and let it snowball into something huge that paralyzes you from taking action. Take the time to look at the negative thoughts in your journal and ask yourself as objectively as possible: is this really a rational thought? Is it really true that I’m incapable of ______, or so-and-so will happen if I try to ______?
At this point, when you’re writing down your negative thoughts, consider the actual, rational reality of that thought and write it down beneath the negative thought. Here’s an example from my journal:
“Thinking of the accomplishments of my friends makes me feel like a failure because I haven’t achieved anything yet.”
“Everyone goes at their own pace. I may not have done anything yet, but I’m working toward it. If I keep working at it, I’ll eventually have accomplishments to be proud of.”
You have to train yourself to think differently. Try to eliminate emotion and be rational. In the example above, my response to the negative thought wasn’t a silly optimistic fantasy; it was a realistic evaluation of the situation. Things are rarely as bad as they seem, and when they truly are bad, there are ways to fix them or alleviate the badness. Instead of walls, think about windows. Instead of wondering about how bad things can get, think about how they really are and what you can do to make things turn out best. There are always options.
I hope this method works for you. Good luck.