One thing I learned in the Marine Corps that I believe can help anyone with any type of goal, be it personal or professional, is that excuses satisfy only the person making them.
I have found it far easier to correct mistakes than to try to pass off an excuse for why a mistake was made to an irate customer. At the end of the excuse, the mistake will still have to be fixed and if excuses become your calling card, you could run out of customers fast.
I have yet to meet the customer that really cared about why something went wrong and that's where they confuse you, what they should be asking and what you should be answering is what are you going to do to make things right.Nothing else matters.
Aside from business, excuses often keep people from achieving their full potential. People will think of a million reasons as to why they can not do something however they should be focusing on how they can overcome these obstacles and do them anyway.
Remember, creating an excuse is just your minds way of giving up.