Summarize this article:

Panic attacks start in the central nervous system, which controls everything from your breathing and heartbeat to your perspiration and respiration. When your brain senses danger, it sends signals to the body through the cerebral cortex to mobilize a response. This happens automatically with the release of chemicals like adrenaline. The heart beats faster. Your breathing becomes rapid. You start to sweat. This “fight or flight” response is not always accurate, though. Learn more about anxiety, panic disorder, and the fight or flight response in books, articles, or online. You will discover that what you feel during a panic attack is very real and that you are not simply imagining things. Some therapists advocate “accepting” a panic attack. Your fight or flight mechanism is powerful but not always right, and you are almost certainly in no real danger during an attack. Try to keep calm and assured if you feel an attack approaching. Don't give in to your fear. In fact, “phobic” or negative thoughts – i.e. “I'm going to die” or “I'm going crazy” – can not only overwhelm you but exacerbate the attack. Consciously force yourself to recognize that there is no threat to you. Hold this in your mind and repeat it for several minutes. You may try to avoid situations that make you anxious. This is natural, but not helpful. Evasion can actually exacerbate your fears. Learn to control your breathing. Draw slow, regular breaths through your nose and exhale out through puckered lips, inhaling to the count of five, holding for five seconds, and then exhaling to the count of five. This deep breathing can help to relieve symptoms of panic, especially hyperventilation, which causes giddiness and lightheadedness.  Another effective strategy is progressive muscle relaxation. To do this, tense and release various muscles working your way from your head to your toes. Tighten each muscle while breathing in, hold for several seconds, and then release. This relaxation technique should reduce your tension and overall stress level.  Practicing yoga or meditation every day are also good ways to reduce your stress and tension. Take care to avoid things that increase your overall levels of stress, anxiety, and tension. Avoid caffeine and other stimulants, for example, like coffee, caffeinated tea, sodas, and cigarettes. These can provoke panic attacks in susceptible persons. Likewise, try have some fun every day and to get adequate sleep each night. Making lifestyle changes is important. According to a recent study, a regimen of at least three workouts per week can curb panic attacks and related symptoms. Although the exact mechanism is not clear, physical activity increases heart-rate variability and has a positive impact on the brain and on mood. Try some form of vigorous aerobic exercise like jogging, riding a bike, swimming, or playing a sport. Go for a walk. Do something active.

Summary:
Learn about the root causes of panic. Don't be reactive. Practice relaxation techniques. Minimize stress. Be physically active.