Psychic vampirism help

I try to understand all the things to know about psychic vampirism because I have more things to do than practicing astral projection and stuff I can practice psychic vampirism because it’s more visual and imagining tendrils and feeding I have a hurdle I want to feed on a colleague to see if my feeding is working if they start yawning but my colleagues are not staying in one place for the ones asking I’m not going to put their energy into myself I’m going to put it in the ground because I only want to see if it’s working can I see or feel if it’s working on myself what is the feeling I need to feel to know it’s working I want to know if it’s working because I want to make sure before feeding on the real target