My East Coach speech coaching Fripp Associate Sims Wyeth gives us this public speaking advice.
You are more convincing when you visibly enjoy the beliefs you want others to accept.
To achieve infectious conviction, rehearse. Rehearsal helps you to find the thoughts, the words, and the logical flow that give you a feeling of truth. Your appropriate display of confidence in your truth is a form of proof that what you are saying is valid. Visibly enjoy your beliefs.