You are not saying how you feel or what you think today, but others wont know if you do not tell them.
Do not make the mistake of thinking those around you already understand how you feel or know what you think without you telling them. It might seem obvious to you, but others may need this spelling out to them and making perfectly clear. If you are staying quiet because you are embarrassed or you think it makes you weak, airing your thoughts and feelings will gain you respect.