To hold your tongue or NAH

As a child growing up people will always say hold your tongue and be careful and mind what you say. Then after a while you will here if you don't speak up then you'll never be herd of close mouth don't get fed. So my question is when is the right time??? Should you speak up when you feel like your mistreated even if it's by your boss, mom, or someone that is in a higher position than you. If you do should you mine what you say to them because last I check speaking up is saying exactly what's on your mind with out a care and express yourself. Or hold you tongue because even if you say something and it's not exactly what you want to say isn't that still holding your tongue because your holding back certain things not spoken. So I guess you should say anything at all then right now your really hold your tongue huh?? Life is Life fuck it say what you needed to say and mean it, because you never know things always sound different coming on than how it does it our head and certain people the only way for them to hear you is y just say it because hey maybe it's something they need to hear. So yes I don't believe holding your tongue will get you anywhere so just believe and speak the truth and you'll never be wrong, so please don't hold your tongue forever.