We tell ourselves so many lies about in so many areas of our lives. Last year when I was struggling in my relationship with food, weight and body image, I learned a technique called "truth journaling". You write down all your thoughts. Next, you number each statement. Once you've done that, you write the truth for each statement.
This is something we have to keep repeating depending on how deeply rooted the lies are in our soul. Sometimes, we discover a lie buried under another one.
Here is a video giving an example. It's from a Chrisitian perspective but the general concept is still useful.