While I never did do an ag rating, I was provided with a one hour introduction.
Two of us sat side by side in a Pawnee, both of us were skinny but that is the way you got your training.
He got me to do a lot of the flying and we would reach cliffs and go into dam near vertical dives and at least 60 degrees nose up at times in near vertical procedure turns.
I watched all those extremely dangerous chemicals being poured around and watched how the grass and anything else seemed to die instantly.
Then there was another good instructor friend who used to do ag work, until his arms and hands started to shake. Extremely nice generous guy with a young family.
All that I'm sure rings a lot of bells with people who knew them.
For me, I valued my health and fitness.
It was the chemicals that they had to handle that made me decide that Ag work was not for me.