Being reliable is the most important trait you will look for in someone on your team. And being the opposite of it is likely to make you very unpopular with others.
Being reliable means managing commitments well and always delivering. There is an implicit obligation to be truthful to others and/or yourself when making and accepting commitments. It means that we will deliver, come what may.
In the event that something throws us off course, we will do everything possible to get back on it but we will also truthfully assess our abilities and limitations in fulfilling the commitment, and clearly communicate to the parties that we have made the commitment too. If this happens too often, then you are likely unreliable in selecting and accepting commitments.
Being reliable to others is also being reliable to ourselves. We must be self-aware of our locus of control and understand our desire and motivation to complete a certain obligation. If we can’t fully trust ourselves to complete a project or deliver a certain task, do not promise that to others. That’s just being a jerk.
My thoughts 