Just as a warning somethings should not be said at certain times, at particular places or to specific people. Carefully weigh your words before you say them. Remember the adage, "look before you leap" and "think before you speak". If you are speaking in the context of a meeting about a certain subject then don't hesitate to challenge others and express your point of view of course without saying anything that could be found religiously or personally offending. Keeping yourself shut up is contagious to ones self. You'll keep taking the easy way out and silencing yourself.
On another thought, some people are amazing talkers but horrible listeners. I think to make a good speaker one must possess the patience and ability to listen to others and absorb the information before reacting. Speaking and listening compliment each other. People think and speak at different speeds so adapt yourself to different types of people.
