Let's take a quick meaning of a career before proceeding on how to choose a career as a student. According to the new edition of Longman dictionary, "A career is a job or profession that you have been trained for, and which you do for a long period of your life". Having defined the meaning of a career, let us talk on how to choose a career as a student. There are many existing careers in the world, but I will group them for a better understanding.
Some careers involve knowing "how" and "why" that is, the area of natural science. e.g. meteorology, astronomy etc.
Some involve recording, categorizing of information and performing mathematical operation on data. e.g. computer analysis, accountancy etc.