Your word is the single most powerful tool you have to generate the results you want in your life.
You can either honour your word, through thoughtful communication, being clear and straight, doing what you said you would do, and cleaning it up when you don't, OR, you can blurt out what ever thought enters your head, waste peoples time with nonsense, make promises and not keep them, and when you don't... pretend the promise didn't happen.
Honouring your word gives your word power. When people know they can count on you they treat you differently, they trust you, things can happen at a much higher velocity.
And, that's not even the best part. When you honour your word, you trust yourself more, you count on yourself more, you start to get a sense of what's possible through communication alone.
Seth Godin recently wrote Seth's Blog: Precision in language short riff about a writer's use of language. It's not that the writer is wrong, or bad, it's just that it's a waste of time. It doesn't move the conversation forward. And that's just not as powerful as it could be.