I am starting a study of Ezekiel. While I wait for some used books to show up from Amazon, I am reading through the book. There is a great reminder for us all concerning our heeding God's call. In chapter 3 God tells Ezekiel to tell the exiles whatever God wants them to hear. They may not listen, but that is not for the prophet to worry about. God sternly warns Ezekiel that if He wants to warn the people and Ezekiel does not convey the warning and that person dies, then the blood is on Ezekiel's head.
How can this be applied today? If God compels you to say something to an individual, you had better do it. If I am preaching, I had better say what God has placed me in the pulpit to say. If I am on a mission trip, I had better share with whom God wants me to share. If my neighbor says hello and God tells me to invite them to church or engage in conversation, I had better do it. He may have greater things for that person than I realize. I do not want to be the vessel that won't share His word or message.
If God tells you to speak up, then speak up!