I believe that service is a function of who you are, rather than what you do. I have met people in healthcare who are superficial, while one of the deepest thinkers I know spent his entire working life in insurance. Make your service how you live your life: loving, real, generous, intelligent--so that whatever your field of endeavor you will help the people in it and through them the greater world.
After that, your choices will become clearer and in many ways, the choice of work will matter less because it will be informed by who you are. Any choice that interests you and that pays the bills well enough will likely be right enough.
As Gandhi (I believe) once said (not verbatim): "Is the street sweeper or the cobbler not noble by the honesty of his work and the kindness of his soul?"
After that, your choices will become clearer and in many ways, the choice of work will matter less because it will be informed by who you are. Any choice that interests you and that pays the bills well enough will likely be right enough.
As Gandhi (I believe) once said (not verbatim): "Is the street sweeper or the cobbler not noble by the honesty of his work and the kindness of his soul?"