Standing tall and proud is a powerful weapon when you are presenting. The audience reads that posture as belonging to someone who is sure of himself, confident in what he is presenting and immensely passionate. You’re not slumped over. You’re not looking like you just found out your cat will never get into college. You believe in what you are saying.
And the audience buys every word. All this from imitating how Arnold Schwarzenegger stands.
Just make sure you don’t talk like him.