You should decide to do things you are mostly passionate about. It is the combination of the fields, such as engineering, arts, philosophy, etc. that do amazing things combined efforts together.
If you are thinking whether you should be an engineer, then I can tell you that it is a very interesting and very challenging path. You will have to learn and understand new things all the time, but you will be able to see your creations move around doing some exciting things if you decide to go into robotics or mechanical engineering, for example
If you enjoy designing, inventing, creating and a bit of maths and science then engineering is a great field to get in to! I like being an engineer because I like problem solving and challenges. Boris is totally right though, you have to be passionate and enthusiastic about what you do,.