I got into the job market starting with what ended up being 20 years on the floor in precision sheetmetal fabrication. I ended up writing N/C code after the first 5, but those 5 years were an education.
OSHA wanted to require using a pair of pliers to bend parts in a pressbrake. If you missed your stop, the pliers would end up broken in half by the tooling, flying who knows where, and the V-dies would be destroyed. That idea was laughed out of the shop, with management support.
One of the cardinal rules that was hammered into my 18 year old head was...
do NOT approach anyone operating a machine until you knew positively they were aware of your presence and acknowledged it back to you.
Stay away until you were sure you caught their eye, no touching, shoulder tapping or not even a word. It's amazing how much concentration is needed when doing fine work around a machine, and newbies who ignored the above warnings would make me jump right out of my skin.
This was brought home by the pressbrake foreman who had lost the tip of a forefinger on one hand, and the tip of his middle finger on the other.
This can apply to any power equipment, tractors, mowers, anything with an engine or enough power to injure. Teach your kids and young relatives early and much grief can be saved.