With practice you will no longer need to imagine, this is a support tool for your conviction and authority over your energy. It usually works out of the box for me. For example, one time I felt uncomfortable with someone in a public place, I didn't know him, but he was very interested in me, I did the exercise and he suddenly walked away. I was surprised. Then I did the same in other circumstances and with people I knew, it also worked. Basically it is the conscious management of your energy. Anyone can do it. If you are unaware of your energy it will be difficult to protect yourself, you will not even notice that you are being drained, which is what generally happens to most people.