Other than the occasional babysitting (who hasn’t?) when I was young, at 15 I started interning at my dad's office. I did all sorts of things like rip up old licenses for software they didn’t use anymore, organized file cabinets, etc. Basically all the stuff no one else wanted to do!
This was huge for me though, I learned more during my years in corporate internships than I would ever learn in school! I learned that just because you are an adult doesn’t always mean people act like adults should act! I also learned that a lot of people are very helpful and friendly and good at different things. Some people are really terrible at one aspect of a job and amazingly good at another! I also learned that degrees get you in the door but don’t necessarily mean anything. I worked with a woman that had about 3 (a couple of undergrads and a masters) and she was great at spitting back information, but her comprehension and ability to apply the information was greatly lacking. I also found out pretty quickly that working at an internship for a HUGE company also has other benefits – it paid about twice what my friends were making at fast food restaurants and I had set hours! It certainly did spur my drive for career success! And I have never looked back :)