“When you smile to the world , world smiles back.”
Face is poor place to know about someones emotions. Yes its true. As we grow we have learnt to mask our feelings. We pretend to smile. But yes faking a negative emotion is quite difficult. Even psychology experts cannot predict someones personality completely because so many things needed to be considered. Like a single word or punctuation while writing can change meaning of sentence in the same way single expression or body language will alter someones view about you. Single expression can never predict someones mind or mood . Its combination of variety of expressions. Same expression can be perceived differently by different people. Its like honest expression of thoughts noticed by others. We cannot always go by body language but first impression is created by it only . So whoever you are and wherever you come from , how you express always matters. Some power gestures create lasting impression of you on others mind.
Body language should always be natural. It should never look fake. Some body gestures should be avoided. There are no clear rules for body language. Some use more hand and leg movements some use only facial expressions to deliver their point. Faking a particular body language expression makes you feel like that .You start reacting the same way after sometime. So your body has a power to change your mind .
Have a look at some points on Body Language: