Using the model

Hello, I have read carefully all the information about the model. I am wondering how I can help myself to truly believe in the new thought?
Should I keep repeating the thought during the day ? (that’s what I am doing right now and it is quite exhausting).
I know my original thought makes me feel unsecure and anxious, and I know what my new thought should be, but I don’t manage to truly believe in it.
If you could give me some tips to be able to do it, that would be wondeful.
I am sorry if my english is not that good and I hope you understand my question.
Thank you very much for your help