One thing unites almost all successful individuals, proper psychology, and its opposite almost always exists amongst unsuccessful people.  The reasons for this are quite simple. 

Basically speaking, we have to remember that we all construct our own personal reality.  Sure, that sounds like a real new-age kind of psychobabble, but it's also very true.  Maintaining the proper outlook and belief system is key to achieving success of any kind.  For more information on this issue, check out my PrintNPost article about the psychological factors that are present in the majority of successful investors:

http://www.printnpost.com/articles/2917/1/Successful-Investment-Psychology/Page1.html