I don't work yet, but I'm studying electronics engineering (I haven't seen almost any electrotechnics/power stuff though).
The basic courses in the first 1.5 years are almost the same for all engineers. So you will study physics and maths, lots of it.
In electronic courses you basically see circuits made with components which represent physical parameters in a lumped way (e.g. a wire has a resistance that depends on its length, but you draw and think about it as an ideal wire with a resistor in a certain spot), idealized with mathematical models (e.g. V = RI for the resistor). Then the circuits gradually become more complex, the devices gradually become less ideal (more complicated equations and models are used for them, e.g. to describe a certain non ideal behaviour of something, you can put a resistor in parallel to it, which does not exist in reality, but allows you to analyze the circuit, or a capacitor linked to a certain node, which represents a parasitic capacitance you have to represent in some way in your model in order to do calculations, but is not a real component), and you see new ways of combining them to do better stuff, or new stuff. You will also see details about the components and how they're made too (e.g. integrated circuits), and how you get the models you use in your circuits from physics.
If you like tinkering with electrical circuits and like maths and physics, you will probably enjoy it.