Gynecologist - or a sexual health adviser.
I'd love to work in a GUM clinic, I would deal with hundreds of people a week to help with their most basic sexual health needs that will help them and other people throughout their whole lives, and it would allow me to educate large numbers of people. I'd be NHS but semi-private which if you can do if you have a speciality that NHS may be lacking, I'd specialise in menstrual health and that would give me more freedom in how I practice as well as my own office which will be full of books and leaflets to help my patients. I'd start-up an organisation dedicated to less widely-known about women's health issues with a mind on social aspects; menstruation and over-medicalisation of women's bodies, start off as a small web site then work up to a larger organisation. We'd support/fund/carry out research, activism, and provide sex education and 'girl talks' in schools that are body-positive, up-to-date, sex-positive, and not corporate sponsored. I'd also like to work on a medical centre dedicated to disability and sexual health, have in-house GP's and physiotherapy where health care workers can be in contact and working with other areas of the centre. I'd have sex workshops to help various people with various needs, sell different sex toys made for disabled people, and offer therapy for disabled people who have been sexually abused, or for their care workers to help them help the people they care for have a happy healthy sex life while still protecting the care workers from accusations or abuse themselves. Maybe include research in the centre to make it more economically viable.
This is unrealistic on many levels, not least of all because I lack the education and money, it would also be impossible for me to deal with people who would come into the GUM clinic who are knowingly putting themselves/others at risk or who are wilfully ignorant. Can you tell what my 'special interest' is? lol In all fairness biology, medicine and research have always been major factors to my idea of ideal jobs growing up...excluding wanting to be a farmer when I was five-years-old
OR....being a helicopter pilot would be totally cool! 
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Bloodheart
Good-looking girls break hearts, and goodhearted girls mend them.