Negative beliefs can be quite stubborn can't they? It can feel frustrating and hopeless but I can assure you that they can be changed. It takes time and continued effort. Each time you try to change the belief it will get easier.It has taken a life time to have these though patterns set, it will take time to replace these thought patterns with more positive thoughts. Even just naming the negativity and being aware of it can help. May I ask how this core belief was formed?
You might also want to try to work mindfulness and acceptance into your CBT practices. Sometimes when we let the emotion pass over us it loses it's power. Have you heard of mindfulness before?
What you were saying reminds me of my father. Frequently I hear myself thinking that a task that I am doing could or might not meet with my father's approval. Especially when he died 7 years ago. Here I am, worried about meeting the approval of someone who could not give it in life, let alone now! I will be adding this to my list of negative thoughts that need to be challenged.
I am several weeks into the program. Recognizing the Negative Automatic Thoughts has been an eye opener and I can see where this is leading to in the program. The things is, even when I come up with rational alternatives to challenge the Core Beliefs, I don't believe them. I can understand and KNOW that I should heed the rational thoughts. In a way I do believe them. Yet, I hold on to the negative thoughts and emotions. I clutch to them tightly. Even though I know full well they are toxic to my life I cling to them. They are all I know. In my 45 years of life all I have heard is the negative from childhood. My own voice picked up from there.