Do What You Are at the library and learned that I'm heading in the right career direction for my personality type. Of course my path has been far from traditional, but I digress (pun intended).
Despite the hefty almost 400 pages, a careful reading at the beginning will knock the reading down considerably. After an introduction to the concept of personality traits, you decide what type of personality you have. Far from the intensive Myers-Briggs, you must depend on your honest evaluation of yourself. I am one of the 2-3% of Americans who are Introverted, Intuitive, Feeling, Judging (an INFJ).
After deciding on a personality type, there is a short chapter explaining how personalities develop with age. After which, the bulk of the book gives detailed explanations of career choices most likely to suit you. I certainly didn't read all of it, just the section that pertained to my type.
For the casual observer, this is a great starting place. I doubt anyone under the age of 25 will be skilled enough to perform the critical observations required of themselves. Too often we only see the things we want to see. If you are curious about how your personality fits into your work, give the book a try. But if you're having serious issues or problems, don't self medicate - see a professional.