So envious!

How do people decide what they want to do with their lives? I am 25 and I feel no closer to knowing what career I want than I did at 17. I chose a major that I thought I would like and I got into it and just discovered that it was too... political (special education if you wanna know). I took loads of psychology classes and loved them. And some social work classes. The social work classes I took were intro and kind of boring but I think once I got past that, I would like social work as a profession and be good at it.  People are constantly giving me ideas on what I would be good at. I have thought about nursing, education, midwifery, social work, psych (ultimately working with children in some capacity), photography... I have so many interests. How do people just pick ONE thing they want to do and study it? I know there are criteria. 1) my future profession HAS to help people. I have to feel like I am making a positive impact on the world. 2) I am pretty sure I need to work with children or women or both... specifically. But other than those things... not sure how it all works out. If anyone has advice for me, please let me know. I am sometimes very jealous of my husband who, in his like... 7th year of post secondary education really seems to at least be headed in the direction of a career. And I get a little green with envy when I come by people who have figured out what they want to do with their lives and are on their way or achieving their dreams. I feel like I have no defined dream. I would really like one of those...