Degree of Difficulty

I completely agree with the posts showing respect for how hard acting can be, especially because I think that being on stage is difficult. And watching movies with emotional performances (I watched 'Blood Diamond' yesterday) I now can't help but think about how actors who are crying or screaming or dying actually think to a degree that it is indeed happening to them at that moment. I wonder sometimes, also, whether the toughest thing about acting is actually the acting part or whether it is getting into the proper mindset to actually act. For some reason I think that once someone is in that place where they are completely into what they are doing as somebody else, which is clearly very hard to get to, it would be easier to keep going with a character, but I don't know.