The next time I find myself wanting to make an excuse for something that I haven't done or should have done or could have done better I will remember the following from Steve Pavlina.
Excuses are lies we tell ourselves to avoid dealing with unpleasant truths. But as long as we buy into those excuses, we can never move past them. Instead of addressing the underlying problem, we merely hide the symptoms. One of the most important steps in personal growth is to uproot excuse-making and confront the real issues behind the excuses with consciousness and courage.