If you say you’ll do it, THEN DO IT!
If you say you’re going to do something and other people are depending on you, THEN DO IT!

If you don’t do it, then put your ego aside, apologize, and make amends.

There’s no greater sign of selfishness than someone who doesn’t follow through, isn’t reliable, hurts a lot of people in the process, doesn’t apologize, and doesn’t make amends.