Formulate a lecture on a piece of paper to be imagined by yourself. When you have sufficiently memorized what it is supposed to say, find a quiet place where you will not be disturbed. Close your eyes and imagine yourself giving a lecture on stage. You should be able to mentally visualize and hear yourself giving the lecture. After a period of about 10 minutes, stop trying to put focus on giving the lecture and simply think about nothing but the scene. The goal here is to let your subconscious carry on the lecture. This can be used in extra-sensory perception-type applications.
Practice this for two months, note your results.