tl;dr: I was super involved in
theatre in high school and mildly involved in college, but it was a really long process to figure out what I wanted to be doing. The single event that truly got me into what I do now was this random Fringe show I did for a friend-of-a-friend.
The whole story:
In high school my friend and I tried out for a
play. From then on I was hooked and worked on every
play in my high school career except one, in addition to taking several classes (no tech classes, but acting and IB
theatre) and being the president of the Thespian troupe my senior year. Mostly I acted, but I did some costume crew, and some
props design and run crew, and then I did AD and ASM, which I liked more than anything I had done before. My school
theatre department had an "exec board" with a TD, ME, PM, and
theatre manager. Rumor was that I was going to get the
theatre manager position... but then it went to a student who was a year younger than me (which, looking back, makes sense - this is the person who keeps the schedule for all rentals for the
theatre space... give it to someone and let them keep it for a while [wait a second... why was that a responsibility that was given to a student?!]) and I was pretty upset because I was sure that if I had more tech experience I would have gotten the position. I acted in the first two shows in 12th grade but for the final show that year I decided to SM it - I've never told anybody this but the actual reason I chose not to audition for it was that she wanted British dialects (I think there were something like 7 different dialects in that
play, it was ridiculous) but I knew I wasn't going to be able to pull it off and didn't want to make a fool of myself so I decided to try
stage management instead.
Went to college, auditioned for something, realized I sucked. But at the same time I was also doing some scenic painting and some light hangs to help out a professor (and to get extra credit). She mentioned to me that one of the student-directed shows needed a
stagehand, so I did it. Had a couple more crew gigs throughout college, but I was only a
theatre minor so I didn't have the practicum obligations that majors did, and naturally the spots went to majors first.
Four years out of high school, a friend from high school contacted me. "I'm starting a summer camp
theatre program. We're doing a full production. Will you be my
stage manager?" So I did it, and then after that I didn't do any
theatre for another three years. The same friend contacted me saying "I have a friend who's doing a Fringe show and she needs an SM and I already gave her your info." So I did that show, and at the Fringe bar I met an artistic director who invited me to work with him and I've been working professionally (in
stage management) nonstop for the two years since then.