All of us know someone who NEVER does what they say they will do. That person whose only consistent action is disappointing others. Then there are those who seem to offer unsolicited favors that never come through.
How do you feel about them? You may love them but do you trust they will come through in a pinch? Probably not. They are not the person who you would put your confidence in to carry out an important task.
Now, the question is 'Are YOU that person'? If you are, understand that the lack of dependability affects both personal and professional relationships and opportunities.
I encourage you to think about how you feel when someone doesn't keep their word to you. Think about how you feel when someone lies to you - intentionally or unintentionally.
Be more careful about what you promise to others (and even yourself). Let your yes mean yes and your no mean no.