"When I was 12, my family moved down to Wilmington, North Carolina, so my dad could open up a store called Hanover Hardware. Of course, he put me to work and I did everything from stocking shelves to waiting on customers.
"Eventually, I got paid around a dollar an hour, which I spent on things like gas for my car. Remember at the time, gas was only 25 cents a gallon.
"Later on, my dad expanded into appliances, so I had to learn how to install refrigerators and stoves and washer-dryers and air conditioners. To this day, I'm still pretty handy. At that job, I learned a lot about responsibility, how to deal with people and interact with customers. It was a good start in life - and I've been working ever since."
Thomas Peterffy: Founder, Chairman & CEO, Interactive Brokers Group
Estimated net worth: $11.1 billion
First job: Land surveyor
"I got my first job during summer vacation at age 12 as a land surveyors' helper in the Hungarian countryside. The job consisted mostly of carrying measuring instruments, food and water for the team of surveyors.
"I recall struggling with my heavy load across an endless wheat field in the August heat, trying to hide my tears. They were not supposed to hire me under 14. Living in Budapest, this was my first opportunity to see how people lived in the country. I slept in a barn on a hay loft.
"At the time, all the lands were cultivated as socialist communal farms, but each family was allowed to have about two acres of their own around their house and a few animals. This was where the bulk of the food for the nation came from.
"This experience led me to study civil engineering, and when I came to America at age 21, I eventually became a computer programmer."