Why do people like to hide their feelings ?

These past few weeks , i've wondering, why are people so afraid to show how they feel or what they want to do or be? Ok i must admit i'm not such a open person, but if you dont do anything people might never know what you really want or know how you really feel. You should learn to be more open and believe in yourself even when no one supports you. Of course i'm not saying you should go to the extreme of being rude and doing extremes . Dont be afraid , stand up for your rights and needs . If your still confused, pray to God and he will guide you on you calling and life. :)