How to Become a Full-Time Investor

Recently, I received the following email from a RealMoney subscriber:

Currently, I am in a transitional stage in my career, moving from a small business owner into a stock trader/investor.

As a teacher, you no doubt encounter many young, enthusiastic students ready to leave their mark on Wall Street. Undoubtedly, many succeed while others (probably many more) fail.

Would you pass along a prevailing trait -- maybe to the most prevalent -- which you believe separate the successful vs. the unsuccessful investors? ...