Certain jobs require a distinct personality. There is little point in pursuing a job in communications if you are not an extroverted person who loves to interact with people. If your soul bursts with passionate creativity, you are not likely to be content with a job in accounting. Personalities are like shoe sizes. They are not subject to our choice or preference, but they can be occasionally fudged—with uncomfortable consequences. It is neither an accomplishment nor a fault to acknowledge that some people can speak before large audiences and be exhilarated by the experience while others would be petrified. Some people can study an equation for years and be fascinated by it, and others would long for human interaction and variety. Realize who you are—what your true personality is—and choose a future that fits it.

Even as people experience different phases of their lives, including career and family changes, their underlying personality remains constant after about age sixteen.
Barto 1998