One of the biggest causes of unhappiness is our need to defend ourselves.  Our need to defend ourselves causes us to do and say things that we later regret.  And even if we don't end up regretting we end up harboring anger towards others - even strangers.  

I must admit that I myself have been the worst at this.  I have spent the first 30 years of my life constantly finding reasons to defend myself.  When I was little my Mother would call me her little attorney.  I could defend anything and anybody.  Sometimes its not a bad thing.  At least 1/2 the time I was defending people that weren't present to defend themselves.  And I think that having the ability to see from the other persons perspective is a good thing.  But I bet many of you are like me - only taking the time to see the other persons perspective when the situation has nothing to with you personally.