This question is a particular favourite of relatives with moustaches, (and yes, they include aunts) at family gatherings.
Think of the things you enjoy. If you really enjoy one or two subjects at school, investigate which professions they could lead to. In any particular field there is a wide variety of possibilities. If you really like music of any description, you could, for example, become a DJ, a rock musician, play in a symphony orchestra, work for a radio station or become a sound engineer. Bottom line, is that if you can find a way to make a living from something about which you are passionate, you are likely to be happy in your work.