how old where you when you first work on a car

I was 15 years old and my first engine work was on my 71 Honda CL-100. A bunch of us guys were flat track racing around a vacant field one day. After a long afternoon of this, my engine felt like something was pulling it down. I slowed down and it seemed to be running ok so I made another lap and it started smoking a lot out the exhaust. On further inspection, I found a vent tube out the top of the crankcase that had poured out the oil I guessed from bouncing around that rough field.
I babied it home and removed the SOHC head, then the cylinder which was in pretty bad shape as was the piston. I took the cylinder off, took to have it bored, bought the next size up piston and rings, put it all back together, and cranked it up. During disassembly, I tried to be careful not to let the cam chain get slack enough to come off the gear down inside the crankcase. Oops. That didn't work out. So, I wasn't sure if the cam was timed correctly. I then advanced the cam one tooth. Couldn't really tell any difference. Advanced it another tooth... power was down. Then I retarded it one tooth, then two. Same results. Put it back in the center, and all was well.
I did all this on my own with no outside guidance. I just looked at how everything came apart and reversed that for reassembly. Got the torque numbers from the Honda dealer.