Proverbs 16:23 (NKJV)
It has been said that talk is cheap. People use this expression because it is very easy to just say something. But, while it is easy to just speak it can be more difficult and it is more important to have something to say that is worth saying. Jesus set the standard for us and if we look at His life we don't see Him just carelessly throwing words around or continually having to apologize for saying the wrong thing. Jesus chose His words wisely and we should do the same. Jesus said that He only spoke words that His Father taught Him (John 8:28); that is something that would be good for us to imitate.
Sometimes people say things that are not very kind and not very good. These same people might try to justify what they have said by making the comment, "Well, I didn't really mean that" or "OK, I know what I said was not really right but you know what I mean". Saying things that can hurt or cause a problem for other people is never a good thing. We need to say what we mean and mean what we say. We should have a good basis for what we say; we cannot allow ourselves to just say anything at anytime. The Bible should always be our standard for how to live our life and for the words we speak.
We need to be wise with our words and choose our words carefully. This is something that all of us can work on for as long as we live. But it is not an impossible task and Proverbs 16 gives us a key about how we can say the right words, we teach / train our mouths what to say by what we have in our heart. If we fill ourselves with God's Word then it is easier to be able to find the right words to speak. Jesus said that it was out of the abundance of the heart that the mouth speaks (Matthew 12:34). Fill yourself with the Word of God and don't just say anything that comes to mind, teach your mouth what to say about yourself, others, and your life.