What I Learned Today: Why Intelligent People Fail

Among a list created by Sternberg, R. (1994). In Search of the Human Mind. New York: Harcourt Brace:

• Lack of motivation
• Fear of failure
• Procrastination
• Wallowing in personal difficulties
• Misattribution of blame (when it goes well, it's due to our actions, when it doesn't go well, someone or someone else is to blame)

I claim ownership to all of these reasons, in my personal life and as a teacher.  How about you?  Add to the list?

More info can be found here