From Daily Mental Practice by William Chandon, PhD.
Sit in a comfortable, quiet place, where you can close your eyes and fully relax. Take a deep breath and relax your body. Then take another deep breath and relax your mind in the same way. Imagine you’re in a magical place where you can do anything and be anyone you want. Now slowly repeat your power word (words such as "confident" or "flow"). As you do, imagine practicing and competing with exceptional skill. If you’re distracted, gently bring yourself back to repeating your power word. After mentally practicing for 15 minutes, take a few deep breaths, stretch, and give yourself all the time you need to feel refreshed and ready to go on with your day or night.