The most important predictor of success is determination. While intelligence certainly helps, it's not the deciding factor. There are plenty of people as smart and intelligent as Bill Gates but haven’t achieved anything. Even in the highest of high tech industries, success still depends more on determination than brains.

     The simplest form of determination is sheer willfulness – wanting something so bad, you must have it, no matter what. A good deal of willfulness is inborn, because it's common to see families where one sibling has much more of it than another. Circumstances can alter it to an extent. Bad circumstances can break the spirit of a strong-willed person. Bad circumstances can also at times make a weak-willed person stronger-willed.

   Being strong-willed is not enough, however. You also have to be hard on yourself. A person who is strong-willed but self-indulgent, cannot be called....