lost&confused

Hi Everyone, I am currently a first year MBA student at Wharton, Upenn (4 months/1 semester into my program at one of the top MBA programs in the world). I have been questioning my career choices and going down the MBA path, I have always been interested in the medical field but since I am nearly 5 years out of undergrad and have not taken any of the science prereq classes necessary, I have always convinced myself from making such a radical switch. Now that I am in the MBA program I have seriously been giving thought to the option of a nursing career. I have been agonizing over wether it is logical for me to continue doing this MBA. I can barely motivate myself to do any work (but I'm still passing) and feel no passion or call for what I am studying and can't even find a job or company I can imagine working in post MBA. The thing that gets me is I can't get past the pushing paper, cubicle 9 to 5 job. My aim in life is not to make as much money as possible, so clearly I'm already in the wrong place. When I picture being satisfied in my career I think of high practicality, down to earth, high pressure, active but somehow still very hands on, the more to show for my work the better. I know nursing is not for the faint of heart, and while I can't say I can imagine exactly what walking in the shoes of a nurse is like I've done my fair share of volunteering and most of my experience is in nonprofit down and dirty programs like AmeriCorps. I like to think if I can put up with being responsible for other people's lives 24/7 and sleeping in church basements all to be of service to small communities, I can hack it out in most jobs. Its my motivation that drives me, and I've lost it. A couple of questions: Does it sound like nursing would bring that motivation back from your experience? am i crazy to want to leave a top MBA program people would die to get into? is really a logical and realistic option for me? ... i would already be starting out at a disadvantage since i'm 26, now in debt from the Wharton MBA (although better to stop now than a year in), and still unsure of the best path for me... am i just soul searching when instead i should be sucking it up and stick through this? i must disclose, i seem to have unfortunately developed a track record as a habitual career hopper through this quarter life crisis. any thoughts, guidance, feedback, personal experiences, recommendations, anything really, would be much appreciated!