I guess I was about 12 years old. I spent an entire winter shoveling driveways in my neighbourhood, and then cutting lawns the following summer so that I could buy myself a mini-bike. My parents told me if I saved half the money, they would put up the other half.
I got a custom mini-bike, pull start engine, and it went about 30 mph at full speed.
I wish I had a picture of that thing...