If you know yourself well, you can develop work situations you like, and avoid work environments where you might fail. Typically, and in the hands of a certified interpreter, testing can help discover where your success path likely falls. Career tests require an investment of time and money. The time committment, secondary to most people, is actually more important to consider. Armed with test results, you may need to spend time in library research or informational interviewing.
Behavioral changes are often in order.
This might include seminars, books, tapes, or actual practice necessary to change areas that would suit your overall career direction. If you have the opportunity to take career tests, please do. You can never know too much about yourself. In general, the better you know yourself, the easier it will be to design a satisfying work and lifestyle.