Do I speak up or keep silent??

Ok, so how do you know when you should speak up if something is bothering you or if you should keep silent?? Sometimes i want to speak up, but i can't figure out the correct words to say...So sometimes i keep silent, but i know there will come a time when i will need to speak up, i guess i am just not ready at the moment. Sometimes i have to think about it, or sit in my pity pot a bit, or just keep taking it and taking it until i can't take it anymore. Then i know it is time to speak up. I don't rush these things like i use to, i know when the time is right, i will speak up for myself..