I think I was 12 or 13 years old but I spent a summer with a steel worker who had a tree removal business on the side. He was one hard core, crude guy. But in his basement workshop was this motor. It was a Mercury 2 cylinder 2 cycle engine from a 2 man saw. It looked like it had a blower intake on top of it. I had to have it. I worked for a long time to earn it and used it on a homemade go-cart.
There are all kinds of engines around and what can be done with them. And a mentoring neighbor. That was the start to my career at that age. My parents hated it but couldn't stop me because I worked for my projects. It taught me to never shut my kids' projects down if all they needed was a little help and they stayed with it.... You just never know what can happen.