What you are describing is also labeled self hypnosis. I was trained in hypnosis back in the 70's at University of Texas. Quick tip for those who want to try this. Create a phrase in your mind that you will use to go into a deep state of relaxation. Using the Greek alphabet is one way. For example keep repeating to your self “Omega Bravo” over and over as you push out all your day to day stress and distractions. Just focus on becoming completely relaxed as you repeat your personal phrase. Over time, just repeating the phrase to yourself will allow you to rapidly become relaxed. Then focus your imagery on your goal and how to get there. I have used this technique for over 30 years. Test anxiety, performance anxiety, etc, while not reduced to zero, are now manageable and no longer interfere. Good luck everyone.