Here in Germany, depending on the type of school you visit before, you can start an apprenticeship from early as 15 which is also the legal minimum.
The decision that my Job had to be something electrical was already made when I was still in single digit age. The hardest part was actually the first months of the apprenticeship, manual metalwork. Days of filing, grinding, sawing. Being an apprentice in an industrial plant, most of my work was indoors, unlike a classical el. contractor working in buiding construction. I imagine the weather and temperature being quite a hard part when you are in construction.
Funny, i just realised filing metal and filing paperwork is the same word in english.
Ah well, the final exams were a hard part too. The company where i was an apprentice didn't really teach us anything except we were taking part in the daily work life, while in other companies the kids really had people teaching them electrical theory.
How is it done in the US? Do electrical contractor apprentices visit classes? Over here, most apprenticeships run parallel in the business and a public vocational school. Depending on the type of Job, you go to vocational school 1 day per week, or you do blocks of 2 weeks school, 6 weeks work, and so on. You would basically have to intensify what you learned in the 2 weeks school during the following 6 weeks work, with the help of your trainer. But we didn't have a dedicated trainer and we just worked and forgot much from school, until the next school block started.