I worked stuffing envelopes, copying, stapling, sorting and occasionally moving heavy stuff around from when I was old enough to do so constructively. I had three siblings and those of us old enough to help would line up like a little assembly line. In the early days this was mostly for activist semi-political causes. Later there was a family small business. Eventually after our friends started helping their parents asked that they be paid, so we were paid too. About US$10/hour in today's money. We had a great time helping mostly because it was very rare: we'd assemble mailers maybe 3-4 times per year and do some physical labor maybe 1-2 days per year. I still have a great fondness for the activities. Before we had kids, my wife and I helped all our acquaintances move. Most of the time we were the *only* people they asked to help. When we moved once we invited most of them to return the favor and had something like 20 people show up. There was literally no way they could all help at once. Fun times.
The first real sustained job I had was handling data entry and inventory balancing for the aforementioned small business. I did this job one spring alone (normally more people would work on it). The job was paid for as a single lump sum, not per hour. I type very, very fast on the keyboard and numeric keypad. I made about US$70/hour in today's money. I'd get home from school and work on it an hour or two every day and then a bit more over the weekend. I saved it all and that's how I paid for college tuition.