One of my favorite scenes is in Michael Mann's 'Manhunter'
The main character Graham is trying to track down a serial killer and in order to do that he must start to think like the killer which means he must shut out his life. When he finally gets to that point he is alone in a restaurant and looking at himself in the reflection of the glass knowing that he has blocked out everything in his life including his family to search for this killer. His reflection is his other self. The one with no attachments. The one with nothing but what he must be in order to do what he needs to do.
From the first time I saw this film this moment stuck out to me and has always remained. It creeped into projects I was doing without realizing it. Not just a moment of seeing ones self in a reflection (which I have done) but that character realization that they must become something else in order to do what is called for. Even if what they must become isn't something along the same lines as thinking like a killer but just the moment when they know that in order to overcome what they are facing they do need to be something different than what they are. It's a theme that has been in everything I have done and will no doubt continue to be.
Here is that scene. While brief it is one that is vital to the film and to my own creativity.