I agree with jpb on this. I was older, approaching 40 when I started looking for more out of my work, which I had liked quite a lot over the years, mixed with some serious unhappiness. But, at 30 I had started taking art lessons after work, and over about six years, become a painter on my own, and gotten more and more interested in doing something somehow involved in that to earn a living. (I never thought I'd break into some art limelight.)
I signed up for a drafting class at a university extension, with no big idea of getting into drafting for a living, just something I'd like to know how to do, just as I had learned caligraphy, but I enjoyed the class. Turned out everyone else in the class was studying landscape architecture. What? What is that? So, I signed up for a second class, elements of design.
My life just changed with that class, thank you, Nori.
My previous life studying science and running/handling labs wasn't a loss, it was still part of me. My interests became more complex over all those years.
I looked back and thought I was bonkers to pick science in the first place, re my own real interests. Took me a while to figure out I was/am complex mix.
I think it has been hard for people to figure out what they really like before getting catapulted into making a living. It pretty much always has been. A lot of people, maybe even the majority, change what they want to do over time. It's harder to change now than in the recent past in that just having a job is a good thing. But humans are still the same..