This is a good question. Sometimes you are too young to know, but you will know as you grow.  Your intuition will tell you what you want to become, a doctor or an engineer or a nurse. As you grow, your intuition will tell you slowly what you like and what you dislike. Let's say that you want to  become a  nurse and you went to school. After one year you did not like it and you decide to drop it. So now try something else. There is nothing wrong in trying out something new. At first, most students don't always know what they want to become.

It is not always necessary to know what your parents want you to be. You are naturally influenced by your parents because if your dad is an engineer then all you hear about is engineering. That should not be the goal. You should become what you really like to become. Don't choose simply because you are influenced by your parents or neighbors but because you are independent and you have interest in certain things. It may be different from what your dad or anybody else wants.

You may often change your mind about what you want to be so don't get stuck on one thing. You may want to be a doctor but you may not be qualified to be one. If  you are qualified and smart enough to become a lawyer or a doctor then you might want to go for that. Don't let others force you, including your parents.

Consult your conscious and how you are doing in school. Lets say that you want to become a pharmacist. Then you should go and meet pharmacists or doctors.  See if you really like their jobs. Ask the doctors if they are happy, what kind of life they have and if they are not just after money. Do they  have time to spend with the family? You should investigate whatever you want to become. There is nothing wrong with that at all. Then you can become an engineer not because your father is one, but because you want to be.

Some people become engineers against their wish. They are not good in mathematics and they have trouble later on.  First, you should be good and capable in the field you choose know what it's about. Be sure that you take time to choose your line before you jump in.

-- Swami Radhanandaji