Well, pretty much everywhere I read, I see the words from great actors "Act for yourself. Don't worry about who is in the audience, whether they be critics, etc.Worry about getting the other person to do what you want." That's not a direct quote or anything, but it's close enough.
Yesterday I was rehearsing a scene and I felt so on and I didn't worry about the director saying it's wrong, I just went in and tried to affect my scene partner, and I felt so alive in the moment! I went to my other rehearsels, and man! I did the same thing! I was concentrated, energized, and pumped! I didn't feel like I did it perfect, but I did get a little big headed.

Today, I went in to rehearse the scene again that I mentioned first, and I felt like I sucked and not in the moment, etc. The only explanations I could think of were a) I was a little big headed, b) I was trying to show off to someone, c) I had set my expectations too high.

So, what I'm asking is, how do you deflate big headedness when you start to feel it right before you go on-stage? I have a tendency to beat myself up, and then I can't concentrate and it's all down hill from there. Or, how do you try and get rid of the "I'm gonna knock their socks off." thought and concentrate on the moment? A long question, but I'm interested to see what ya'll tell me, and I need the advice!

Thank you!

By the way, I'm not usually a very cocky person when it comes to theatre. I usually don't feel good about what I did at all. Just so you know.

Interesting topic! Well, all of us (performers) have a little voice in our heads that says, "this is what I'm going to do, and people are going to love it". I don't care what anyone out there says, we act, because it is self-gratification at its best. There is no other feeling like it on the planet. Now, how do we get that out of our heads so it doesn't interfere with our work? We all have our own ideas about how to concentrate. Its good to see you have addressed this question to yourself, and you're searching for a way to control it. Being in the moment is, in some ways, tantric. There is a threshold we pass when we get into the "zone", and many actors are self-aware, and know its happening..even as it occurs. It is a great feeling. Sometimes, it only lasts for a moment, and then we're back inside ourselves working out the technical issues we routinely do when we want to make a stellar performance. This is a hard thing to work out. As actors (especially stage actors) have a burden to bear. We have an audience right smack in front of us, so our performance cannot be a self-indulgence. Self-indulgence is for the classroom. On stage, we have an obligation to play for those who bought the ticket or snuck in the backdoor. A key to staying in the moment is truly listening to your scene partners, and truly reacting in the way your physiological self wants to in that specific frame of time. But its a learned thing for an actor to attain that, and reveal your work to the audience at the same time. It's the technical side of acting fighting with the creative side that seems to happen. How do we make them work together, rather than watching helplessly as they pound each other to bits? For me, its that same little voice in my head that says, "keep it going for them. I've trained my head to speak differently. Instead of turning the work into a self-indulgence, my inner voice keeps me connected with the audience as well. My concentration has developed a "split-personality". One who works for the moment-to-moment occupation of the character, and one who works for the observer. I don't know exactly HOW I managed this idea...I may be a little insane...but I digress. The point here is, you've tackled something that most actors are too afraid to admit. So, kudos for bringing this whole topic up!
I have somehow managed to get my "two brains" to work together, and yes, it doesn't ALWAYS work. I find myself stressing about what bills I have to pay the next day in the middle of a scene sometimes. Sometimes, I break that cardinal rule of looking into the audience because there's a smoking hot chick in the front row giving me the "do me" eyes...at least that's what I'd like to think shes going for. Our concentration can, and does trail off sometimes. Sometimes, its for the sake of looking great for the audience, sometimes, its for random reasons your psyche conjures up. JBActors made a great remark once about focusing on a specific object, or point of reference onstage just before taking that step out there. Your mind then focuses on an inatimate object, rather than what you're "going to do". It relaxes the mind so it can go to work at what its given intentions are during the scene. We all have ego, we all have indulgences, and we have to set them aside when we work. Its hard, we're human, and we have layers, just like our character's do. Find a way to tame your inner voice. Take time in rehearsals, during the day, in the shower, whenever, and wherever to get control over your thoughts in these situations. I don't know. I'm interested to see what others say! Thanks!

you are thinking to much just go with your impulses and do what u feel is right in the moment remberin always to stay in the moment and ull be fine

Well, in a generalized way, you're right, but you're missing out on soooooo much! Yes, you need to stay in the moment, but the concern is "how"? If you keep "remembering" to stay in the moment, you won't be in the moment because your mind will be telling you to stay in the moment. Concentration can be tricky for some, if not most actors. Many actors can concentrate for a few seconds, maybe a minute or two, but then something from "real life" creeps in, and breaks concentration from the production. Its hard to maintain that concentration. How do you do it afool?