Trying stuff, lets you test it, just like test driving a new car, walking into a department store and testing new perfume or cologne and for all kinds of products. And we have trial periods for important things like a job or career, relationships. But we stop short and adopt a mind-set of us wanting to fit into, rather than having the mind-set of does this fit with me?
Your life/career/job/relationship etc. is not a thing; it’s an experience; the fun come from planing and designing the experience to see if it is a good fit.
The reframe for the question “What do you want to do when you grow up?” is this “Who or what do you want to grow into?”.