I worked for 3 yrs (as a joint EE/CS engineer) after finishing my Bachelors degree in physics at age 21. I went back to school at age 24, for PhD (in experimen

I worked for 3 yrs (as a joint EE/CS engineer) after finishing my Bachelors degree in physics at age 21. I went back to school at age 24, for PhD (in experimental condensed matter physics). On one hand it was hard going from earning a nice salary to very little stipend. But on the other hand I came in freshly determined, where some of my fellow incoming students just in from their undergrad days weren't as into it. I was certainly above average age for the incoming student class, but there were a few other students in similar situation, and some had worked even longer before coming back to school. I also changed fields again afterwards. Towards the end of my PhD I got a bit fed up with he daily realities of life as an experimental physicist, and almost by chance found my way into an internship as a quant in the financial sector. I enjoyed the internship greatly, and afterwards wrote up my thesis and then started working at the same company. It's interesting because up until around 1-2 yrs before that internship, I never would have thought I'd work in finance. I had no interest from the little bit about finance that I knew. But one day in supplementary course notes during a many-body field theory class, there was a little aside where the prof derived the Black Scholes equation using a Feynman path integrals and it just blew my mind. I had no previous idea there was so much formalism underlying financial products.