Thought download and shifting to positive believable thoughts

Hello, I had just watched Brooke’s thought download and Model exercises. I would like to ask several things regarding them:
1. When you are in the thick of your pain and negative thoughts consume you, how do you find a believable thought that will change that feeling and bring you the results you are gunning for? When you are in a competition or a high pressure and fast paced environment, how effective is the Model in shifting my thoughts to give me the results I desire?
2. Is doing the Model in a particular circumstance supposed to make you feel better and improve performance at that instance? Or does the Model train your brain to look at things differently, so that you are equipped to learn how to shift perspectives and improve thoughts which will come in handy once the negative feelings resurface? I ask this because, I’ve been doing thought dowloads for a while now and using the Model but the feelings, actions and result I want remain theoretical at this point. Could I be doing it wrong? Or is time an essential element here?

Thank you for your time.