I'll openly admit to the fact that I'm not a qualified mechanic with the correct stamped papers, but it's where you start that counts..
My dad owned a couple of dealerships (Ford was one of them), and he had me at the age of 10 driving the cars around the forecourt, and into the workshops.... He also had me doing brakes, and common repetetive stuff like brake pads, bulbs, fuses, oil and fuel filters, etc etc by the age of 12... start 'em young that's what he said....
Then he sold up, and went to diggers, and road haulage... The learning curve took a big step up when you had to deal with the servicing and maintenance of the big stuff like JCB's and 44 tonne trucks...
One day he went out with mum and guests to a boat, and told me (when I was 16), "I want that artic hooked up to that trailer, reversed over the inspection pit, the oil, air and diesel filters changed, the whole artic rig greased where it needs it, all lights and other fluids checked and washed ready parked up outside for me on Monday
I'm late, see you later, have fun......". then left me to it
And he expected it all done that day, no shoddy excuses or crap workmanship, because he went round that artic when he came back, looking at every nook and cranny to see if I'd cut any corners, but never said a word to me... just smiled....
In this day of HSE, no 16 year old would be given that level of responsibility regarding heavy goods vehicles.... lucky if they were given a spanner for their mountain bike...... But this was way in the past though..