When you were a child, what did you want to be when you grew up? Is that what you are doing now or did you take a different turn somewhere along the line and wind up something else? I have found that those childhood dreams may get buried, but never entirely go away. They are deeply programmed in your psyche and aren’t happy when they’re suppressed.
Any career that interests you is fun to research and thus a great one to use for your protagonist. Even if you never got to be what you originally hoped to be, you can do it vicariously through one of your characters.
Who knows what you might discover in the process. It may even motivate you to finally pursue your original dream or perhaps decide it was best left behind. Either way, your subconscious will thank you.