I started out as a flight instructor and charter pilot and it happened that one of my students owned a sprinkler company. Flying was great but I wanted to get married and the money simply wasn't there so I started looking.
My student heard about my looking and offered me a job back in 1975 designing sprinkler systems and it is what I have done for nearly 50 years now. My student told me he felt I would make a good designer because I could read regulations (Federal Aviation Regulations) and see things in three dimensions.
When I started nearly all the work was pipe schedule, NFPA #13 was a little red phamplet and what calculations we did were done by hand.
I will soon turn 76 years old and am still working because I love what I do.