Even in the cliche-riddled land of acting, the phrase "in the moment" carries the most impressive baggage. In evaluating a performance, it is often the first question we ask of ourselves. Was I good? I don't know, was I in my head? Was I "in-the-moment?". Assuming this is a useful way to evaluate how something went (hint: there's more), the primacy and focus we put on the question can skew the process of actually being in it. Too much pressure on ourselves to be IN that we lose the ability to succeed. It's like when someone tells me their name, often all I say in my head is CONCENTRATE! remember-the-name remember-the-name and then I missed the name. It is the difference between concentration and attention.
I came across an interesting blog post from Dr Ian Ellis-Jones, an Australian mindfulness thinker blogger guy (probably not how he would describe himself). In discussing Method Acting he draws parallels between some Strasberg thoughts and the discipline of mindfulness:
Whatever your thoughts on method acting or mindfulness, these words seem very useful as a goal for the right frame of mind for in-the-momentness. It is as much about paying attention in an open way as it is about anything else.