What can and should one do when having a panic attack to lessen the effects of the symptoms?

I use the method of speaking to myself about what is literally happening. For example saying aloud to yourself, "your thoughts are racing, slow it down" or "you're breathing really fast, take some deep breaths." It sounds ridiculous but I've found it has helped slow my thoughts and breathing during panic attacks to help me calm down.

Focus on your breathing by following breathing exercises and listening to calm music. When you control your breathing, you can control thoughts and it becomes easier to calm yourself down again. But always make sure to talk to someone if a panic attack occurs as it really helps to have someone there to be there for you and to support you.

breathing exercises can be really helpful to cope with a panic attack, because it can help trigger the response of the parasympathetic nervous system, which is responsible for calming you down. grounding exercises can also help by encouraging you to focus on reality. a common one has you find 5 things you see, 4 things you feel, 3 things you hear, 2 things you smell, and 1 thing you taste. and lastly, even though it's really hard to believe in the moment, the panic attack will pass, and you're going to get through it and be okay soon.