I am a research scientist/professor in academia, which is not really considered as a helping profession. But it involves a lot of mentoring of junior scientists and other staff, which sometimes goes a bit beyond simply supervising their work. I also do a lot of service work that I am not paid for, for example peer reviewing. Privately, I do writing and consulting for various clients. What motivates me best is not the helping aspect per se but doing whatever interests me personally. I don't think I would be good for classic helping/service work if I did not have personal interest in it. I do very much enjoy when the work goes beyond my solo interest though and have broader implications and even all of my research areas (most recently mental health) have had that element, even if I am not directly involved in the application, treatments etc. I would not want a profession involving constant communication with people though as I am more an introvert than not and enjoy long hours doing research, analysis, writing on my own, in my office or at home. Like others mentioned, I do get emotional rewards from the interaction aspects of my work that I don't really seek that much in personal life. I can easily imagine that many Ts experience this, too.