How can I bring myself down once I have started to have a Panic Attack?

Try clapping your hands to match your breathing and then slow it down. As you slow down your clapping your breathing should follow.

The most simple answer is to breathe. Focus on one thing at a time- starting with your breaths. Breath in through your nose slowly, counting to 8, then breathe out through your mouth again counting to 8. This will focus your mind and level your breathing- in turn easing the chest pain and calming you down.

Just breath, and maybe listen to calm music, talk to a friend, or talk a walk outside in the nature

Well the first thing that I learned about panic attacks is that you have to breathe first off. When you take some pretty deep breaths in and out your sending oxygen to the body in area that need it such as your heart and brain. And when you can get yourself to calm down. The next thing is that you have to tell yourself that this is going to stop these attacks and do not tell yourself that they are in charge. For your in charge of your body and do not let yourself be fooled by your feelings here. Keep everything real in your mind so that you can bring yourself down in the right ways here.

I usually try to control the voice in my head. I tell myself that it is in my control how I feel and force myself to stop. Then I start to look around me and observe my environment. It is really calming to watch other people, observe the trees, cars, or whatever is there at that moment. I also try to guess what the objects around me are "feeling" based on their position, color etc. Basically I am trying to think of anything but myself and my situation. Another tip would be to think of something good you could do to someone you love. Feeling useful often helps me to calm down.