I've always been fascinated by, and driven to understand, the way things work. The solar system, weather, biological processes, anything. But machines and circuits are things I could actually take apart and look inside without disrupting anything (well occasionally I'd disrupt the family's ability to watch TV or make toast.. if you know what I mean!)
My parents encouraged me to take things apart and understand them, and showed me how to find out more about the pieces inside them. Whenever I get a new appliance, or toy, or electronic gadget, I always take it apart and look inside. Engineering wasn't my first choice in college, but it quickly became apparent that it was the right one. No matter what your discipline in engineering, a broad background (with lots of basic chemical, mechanical, electrical, and economical knowledge) is key.
I feel sorry for kids that get pushed into engineering because they do great in math and science but don't have that spirit of curiosity. This can be a long, tedious career if you don't really love breaking things down into their technological elements and learning how they work.
"Real" engineering work is not exactly what I thought it was. In school you learn a lot about finding optimal solutions and doing things the "right way," but in industry, economic forces become very significant. I had to struggle for a while to learn to deliver solutions that were "good enough." That's why I threw economics into the mid above.