The feeling are distressing, NOT dangerous. In reality, there is nothing that can hurt me here. The anxiety can only go so high and then it comes down. Take slow, deep breaths. Prolonged aerobic exercise causes production of endorphins which produce feelings of euphoria and relaxation.
Exercise improves and maintains good circulation and lowers blood pressure.
Exercise may help to clear the mind of worrying thoughts and anxieties and can encourage more creativity and problem solving. Exercise improves self image, appearance and tends to control weight. Exercise may result in increased social contact and also provide a balance with other activities, eg. Give yourself permission to feel anxious. Calm yourself with positive self-talk.