For me, starting with the work and becoming good at the work, from the time I was in college through grad school, and then into my professional life, is the thing that has helped to crystallize my why.
I think the act of being good at something, receiving positive feedback, being able to help people because you are good at that thing, is the underlying momentum that creates the passion, the motivation, the ‘Why’ to keep going, learning, and getting better.
I wrote this article about that topic. Hope your enjoy.