Thinking of joining.

So this is something new to me completely. I really have. I connection to any sort of military but recently started thinking of joining. I am studying to be a doctor so I don't know if it is possible to join. I also don't know how to go about joining if it is. Do I need to join before med school? After? During? Also should I join Navy? Air Force? Pros and cons of joining each? I guess I'm kind of trying to get a feel of life in the military. How is it when you have a relationship and all that.

Any thing will help.

Thanks.