actions and words

I wonder how some people don't get that your words have to followed up by actions for your words to carry any weight. I say things I don't mean, I try not to do it often, but I think generally when I am sincere I follow through, my actions line up, and if I'm insincere, I don't expect to be taken at face value. Just something I think about from time to time because sometimes the other person doesn't understand why even though they may say something that it can be hard to believe if it isn't shown, seems to be common sense to me...