For some people being natural is boring

Some friend stopped me in the street the other day. He said he had read the book and taken on board the bit about being yourself. But, he said, many people he knew were rather dull. Would it not be a good idea to try to make them more interesting when they present?
He is half right. Some people are quite boring. But do not measure them only on how they behave in the office. After a couple of drinks with their best friends they are often quite animated and interesting.
However, The most important thing is to realise that 'being natural' covers being angry, sad, excited, enthusiastic, etc. All those attitudes are part of being natural. So, yes, it is OK to say to a speaker "How about showing a bit more happiness or enthusiasm?" But do it your way.