I went to the police academy many years ago, so I cannot speak as to how things are done now. When I went through, there was a strong focus on instilling in us a feeling that we were invincible - we could handle anything! And also, that we were better than everyone else: the world was divided into two types of people-- cops, and everyone else. So, I came out of the academy fired up and ready to go "play cop." And I did this for nine years before I was in a bad car accident (off duty) that helped me to really see that we are all in this together.
I watched a lot of fresh recruits, and, sadly, there were those who came out of the academy without that feeling of wanting to go out and make traffic stops and do some real police work. Sadly, because they never matured into good police officers. They were really just there because the pay was good.
I also remember feeling scared on my first real good call, and thinking, "What have I gotten myself into?" But, with help from the senior officers, that quickly faded.